mousikomisyo wo sono mama dasuno de ha naku, matigai ga areba saki ni syuuseisita hou ga ii.

そのまま means as it is, unchanged, or without doing anything to it first.

In this sentence, 申込書をそのまま出す means something like:

• submit the application form as-is
• hand in the application form without checking or fixing it

So the idea is: don’t just submit it unchanged.

Because 申込書 is the direct object of 出す.

• 申込書 = application form
• 出す = to submit / hand in / turn in

So:

• 申込書を出す = submit the application form

The particle を marks the thing being submitted.

This is a very common pattern:

• verb + のではなく = instead of doing..., rather than doing..., or not ... but ...

Here:

• 出す = submit
• 出すの = the act of submitting
• 出すのではなく = instead of submitting it / rather than submitting it

So:

• 申込書をそのまま出すのではなく
  = rather than submitting the application form as it is

This structure often sets up a contrast with what follows.

The の nominalizes the verb, meaning it turns 出す into something like submitting it or the act of submitting it.

Compare:

• 出す = to submit
• 出すの = submitting it / the act of submitting it

Japanese often uses の this way before expressions like:

• のではなく
• のが好き
• のを忘れた

In this sentence, you need the nominalized form because ではなく attaches to that whole action.

Sometimes こと can nominalize a verb too, but here のではなく sounds more natural.

• 出すのではなく = very natural
• 出すことではなく = unnatural in this sentence

In general:

• の often feels more direct and action-based
• こと can sound more abstract or formal depending on context

So for this sentence, の is the normal choice.

ではなく is the negative continuative form of だ / である, and in patterns like A のではなく、B it means:

• it’s not that A; rather B
• instead of A, B

So here the sentence contrasts two actions:

1. submitting the form as-is
2. correcting it first if there are mistakes

You can think of the structure as:

• A のではなく、B ほうがいい
• Rather than A, B is better

じゃなく is a more casual spoken version of ではなく.

It means if there are mistakes.

Breakdown:

• 間違い = mistake(s)
• がある = there is / there are
• あれば = if there is / if there are

So:

• 間違いがあれば = if there are mistakes

This is a conditional form using -ば.

Because ある does not take a direct object with を here. The thing that exists is marked with が.

• 間違いがある = there is a mistake / mistakes exist

So in the conditional:

• 間違いがあれば = if there are mistakes

This is the normal pattern with ある.

先に means first, beforehand, or in advance.

So:

• 先に修正したほうがいい = it’s better to correct it first

It tells you the correction should happen before the form is submitted.

Because 先に is being used adverbially to describe when/how the correction should be done.

• 先 = ahead / previous / earlier
• 先に = first / beforehand

The particle に often appears when a noun-like word is used to indicate time/order in an adverbial way.

So:

• 先に修正する = correct it first

This is another very common grammar pattern:

• verb (past plain form) + ほうがいい = it’s better to do... / you should do...

So:

• 修正したほうがいい = it’s better to correct it

This often gives advice or recommendation.

Because in the pattern Vたほうがいい, the past form does not indicate past time. It is simply part of the grammar pattern meaning had better do / it’s better to do.

So:

• 修正したほうがいい = it’s better to correct it
• not it was better to correct it

This is one of those patterns you should learn as a chunk:

• 行ったほうがいい = you should go
• 見たほうがいい = you should watch it
• 確認したほうがいい = you should check it

Not quite. 〜たほうがいい usually gives advice or a strong recommendation, not an absolute command.

So the nuance is closer to:

• you should correct it first
• it would be better to correct it first

It is softer than a direct command like:

• 修正しなさい = Correct it.
• 修正してください = Please correct it.

The sentence is basically:

• A のではなく、B ほうがいい
• Rather than A, it’s better to do B

With the details filled in:

• 申込書をそのまま出すのではなく、 rather than submitting the application form as-is,
• 間違いがあれば if there are mistakes,
• 先に修正したほうがいい。 it’s better to correct them first.

So the sentence contrasts the less desirable action with the better action.

The subject is omitted, which is very normal in Japanese.

From context, it would usually mean:

• you should correct it first
• or more generally, one should correct it first

Japanese often leaves out subjects when they are obvious from context.

So even though there is no explicit あなたは, the sentence naturally implies advice to the person handling the form.

It can be understood as either, but in practice they amount to the same thing here.

• 間違いがあれば = if there are mistakes
• 先に修正したほうがいい = it’s better to correct them / correct it first

In English, we might say either:

• correct the mistakes first
• correct the form first

Japanese often leaves that object unstated when it is obvious from context.

Yes, it sounds fairly neutral-to-formal, especially because of:

• ではなく instead of じゃなく
• the vocabulary 申込書 and 修正

It sounds suitable for written instructions, workplace advice, or polite guidance.

A more casual spoken version might be something like:

• 申込書をそのまま出すんじゃなくて、間違いがあったら先に修正したほうがいいよ。

The core meaning is the same, but the tone is more conversational.