The preposition oleh most visibly introduces the agent of a passive clause: Laporan itu ditulis oleh Rina “The report was written by Rina.” It can also introduce a cause that directly affects something, and it appears in the formal connector oleh karena itu “therefore.” These uses share the idea of a force or source responsible for a resulting state, but their syntax differs.
This page focuses on the preposition and its placement. The full Indonesian voice system and derivational affixes remain on their dedicated pages, including agents in the di- passive.
Active agent versus passive agent
In an active clause, the agent is the subject and the verb normally has a meN- form. In a di- passive, the affected participant becomes the subject and oleh can introduce the demoted agent.
Rina menulis laporan itu tadi pagi.
Rina wrote that report this morning.
Laporan itu ditulis oleh Rina tadi pagi.
That report was written by Rina this morning.
Petugas menutup jalan setelah kecelakaan.
The officers closed the road after the accident.
Jalan ditutup oleh petugas setelah kecelakaan.
The road was closed by the officers after the accident.
The active and passive versions describe the same participant roles but organize information differently. The active begins with the doer; the passive begins with the affected report or road. Oleh does not make a verb passive by itself. Attached di- on ditulis and ditutup marks the passive form.
Omitting oleh when the agent is adjacent
Indonesian often omits oleh when a third-person agent immediately follows the passive verb. This is especially natural with a short, clear agent.
Laporan itu ditulis Rina tadi pagi.
That report was written by Rina this morning.
Pintu depan sudah dikunci petugas keamanan.
The front door has been locked by the security officer.
Keputusan itu disetujui seluruh peserta rapat.
That decision was approved by all meeting participants.
The decisive condition is adjacency: ditulis Rina, dikunci petugas, disetujui semua anggota. Without oleh, the agent has a close grammatical relationship with the passive verb and cannot be freely moved away from it.
When another phrase intervenes, keep oleh:
Laporan itu ditulis tadi pagi oleh Rina.
That report was written this morning by Rina.
Pintu depan dikunci dengan hati-hati oleh petugas keamanan.
The front door was locked carefully by the security officer.
The time phrase tadi pagi and manner phrase dengan hati-hati separate the verb from the agent. Deleting oleh would leave Rina or petugas keamanan stranded in a position that is hard to parse.
Agent omission is even more common than omission of the preposition alone. If the doer is unknown, obvious, or irrelevant, leave the entire agent phrase out:
Jalan utama ditutup sampai pukul lima.
The main road is closed until five.
Formulir harus dikirim paling lambat hari Jumat.
The form must be sent by Friday at the latest.
English also permits agentless passives, but Indonesian uses them very freely because the affected topic often matters more than the actor.
Oleh is not an instrument marker
English by can introduce either an agent or a means, which encourages overtranslation. Indonesian separates the roles. Use oleh for the agent and dengan for an instrument or means.
Surat itu ditulis oleh Rina dengan pena hitam.
The letter was written by Rina with a black pen.
Pohon itu ditebang oleh petugas dengan gergaji mesin.
The tree was cut down by an officer with a chainsaw.
Rina and the officer act intentionally; the pen and chainsaw are tools. Even when English uses by for transport—“by train”—Indonesian normally uses dengan kereta or naik kereta, not oleh kereta.
English by Friday is a deadline and becomes paling lambat hari Jumat or a contextually suitable boundary phrase. A dictionary gloss cannot decide the preposition; the semantic role must.
Dokumen itu harus ditandatangani direktur paling lambat hari Jumat.
The document must be signed by the director by Friday at the latest.
The first English by corresponds to an adjacent bare agent direktur; the second corresponds to paling lambat. Indonesian does not repeat oleh for both.
Affected causes with oleh
In formal or literary prose, oleh can introduce a nonhuman force that produces an affected state (formal/literary). Natural combinations often involve physical or emotional impact.
Ia sangat terharu oleh sambutan hangat warga.
He/She was deeply moved by the residents' warm welcome. (formal/literary)
Wajahnya memerah oleh panas matahari.
Her face reddened from the heat of the sun. (literary)
Desa itu terisolasi oleh banjir selama dua hari.
The village was isolated by flooding for two days. (formal)
The cause resembles an agent because it is construed as the force acting on an affected participant. Everyday Indonesian often prefers karena or akibat: Desa itu terisolasi akibat banjir. Not every reason can be inserted after oleh. A speaker’s motive or explanation normally uses karena, not agentive oleh.
This cause use overlaps with passive-agent syntax in forms such as disebabkan oleh “caused by.”
Keterlambatan itu disebabkan oleh gangguan jaringan.
The delay was caused by a network disruption.
Here gangguan jaringan is the explicitly named cause of the passive verb disebabkan.
The formal connective oleh karena itu
Oleh karena itu is a fixed intersentential connector meaning “therefore,” “for that reason,” or “consequently” (formal). It points back to a reason already stated and introduces the resulting conclusion.
Anggaran tahun ini berkurang. Oleh karena itu, beberapa proyek harus ditunda.
This year's budget has decreased. Therefore, several projects must be postponed. (formal)
Data belum lengkap. Oleh karena itu, komite belum dapat mengambil keputusan.
The data is not yet complete. Therefore, the committee cannot yet make a decision. (formal)
Write the expression as three separate words. As a connector at the beginning of a new sentence, it is conventionally followed by a comma. In conversation, jadi “so” is much lighter (informal/neutral):
Datanya belum lengkap, jadi kita tunggu dulu.
The data isn't complete yet, so let's wait. (informal)
Do not confuse oleh karena itu with an agent phrase. Itu refers back to the stated reason; it is not a person performing the following action.
Placement and complete complements
Oleh stays separate from the noun phrase it introduces: oleh Rina, oleh petugas, oleh angin kencang. Its complement must be complete and clearly attached. A very late agent phrase is grammatical when oleh marks it, but a bare late noun phrase is not.
Buku itu diterbitkan pada tahun 2020 oleh penerbit kecil di Bandung.
The book was published in 2020 by a small publisher in Bandung.
The location phrase di Bandung belongs inside the agent noun phrase penerbit kecil di Bandung. By contrast, passive diterbitkan has attached di-, while locative di Bandung is separate. Destination ke Bandung likewise uses free ke, while an ordinal such as kedua has attached ke-.
Common Mistakes
Using oleh for an instrument
❌ Surat itu ditulis oleh pena hitam.
Incorrect — the pen is an instrument, not the intentional writer.
✅ Surat itu ditulis dengan pena hitam.
The letter was written with a black pen.
Separating the passive prefix
❌ Laporan itu di tulis oleh Rina.
Incorrect spelling — passive di- attaches to the verb base.
✅ Laporan itu ditulis oleh Rina.
The report was written by Rina.
Omitting oleh when the agent is not adjacent
❌ Laporan itu ditulis tadi pagi Rina.
Incorrect — an intervening time phrase prevents the bare agent from adjoining the passive verb.
✅ Laporan bulanan itu ditulis tadi pagi oleh Rina.
The monthly report was written this morning by Rina.
Putting oleh into an active clause
❌ Oleh Rina menulis laporan itu.
Incorrect ordinary active structure — the active agent is the subject, not an oleh phrase.
✅ Rina menulis laporan itu.
Rina wrote the report.
Writing the formal connector as one word
❌ Olehkarena itu, rapat ditunda.
Incorrect spelling — the connector consists of three separate words.
✅ Oleh karena itu, rapat ditunda.
Therefore, the meeting was postponed. (formal)
Key Takeaways
- Oleh introduces the performer of a passive action and selected affected causes.
- An immediately adjacent passive agent may omit oleh: ditulis Rina.
- If material intervenes, retain oleh; if the agent is irrelevant, omit the whole agent phrase.
- Use dengan for instruments, not oleh.
- Oleh karena itu is a three-word formal connector meaning “therefore.”
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Start learning Indonesian →Related Topics
- dengan: Instrument, Companion, and MannerA1 — Use dengan to associate an event with an instrument, companion, manner, or reciprocal partner.
- dari: Source, Origin, Material, and ComparisonA1 — Use dari to express where something begins, comes from, is made from, or serves as a point of comparison.
- karena and akibatA2 — Distinguish clausal causes with karena from nominal causes and consequences with akibat.
- di- Passive: Subjects, Objects, and Argument OrderA2 — Track patient subjects, demoted agents, remaining complements, pronouns, and word-order changes in Indonesian di- passive clauses.
- Misplacing Passive AgentsB1 — Place Indonesian passive agents next to di- verbs, mark delayed agents with oleh, and choose object voice for ordinary pronoun actors.
- Cause and Consequence in DiscourseB1 — Distinguish real-world causes and effects from conclusions that a speaker draws across sentences and genres.