We have already seen one way to express a reason or cause by using the te form.

Because the train was delayed I was late work.

Here we introduce the conjunctions から and ので which are very often translated as “because”. In fact, we’ve already met the latter as we will see shortly.


In English we can flip the sentence structure around with either “so” or “because”.

I have no money so I cannot go on holiday.
I cannot go on holiday because I have no money.

In Japanese we cannot do this without changing the structure substantially—the reason must come first. For verbs and i-adjectives we add から to the reason to create this grammar.

I will wake up early tomorrow so I’m heading home.
このランプが とてもやすかったからふたいました。
This lamp was very cheap so I bought two.

We can also use から with the polite ending.

Because I have no money I cannot go on holiday.
This game is fun so I want to play again.

から can also be used to give a reason in reply to a question.

MikeWhy are you tired?
YukikoBecause yesterday I was working until 11pm.

With na-adjectives and nouns it requires the auxiliary verb (standard or polite).

The teacher is kind so there are many students who want to take his class.

Note the position of the topic particle. A more direct translation might help with the grammar: “As for the students that want to take the teacher’s class, because he is kind, there are many.”

It can also be used as conjunction in its own right.

ShokoThe sales start at the department stores tomorrow.
KentaThat’s why I want to take a holiday from work.

Using だから or ですから at the start of the sentence is a common way to begin an explanation.

から can also be used at the end of the sentence if we juggle the structure a little. In fact, we have alreay covered all the grammar required to do so.

I wanted to speak with Eri so I called her.
The reason I called Eri is because I wanted to speak with her.

All we’re doing here is modifying the noun “reason”. Further the word “reason” can be replaced with の (the shorthand version of the word for the generic “something” こと) because it is obvious from the context you are giving a reason so we don’t need to explicitly use that word. Take the below, for instance:

The reason I bought a coffee machine is because I don’t have time to go to the cafe in the morning.

This use of の can be somewhat confusing at first. It kind of acts as a kind of “joker” word becoming whatever is obvious from the context. In honesty, this structure is not heard all that often. In the majority of cases (certainly in conversation) you would simply say:

I don’t have time to go to the cafe in the morning so I bought a coffee machine.

Nevertheless, changing from one structure to the other is a good way to test your understanding of the grammar.


We have already learnt the grammar behind ので when こと was introduced to nominalise verbs. At the time it was noted that こと can be abbreviated to の for certain usages. で we already know can be used to express a reason. Combining these two pieces of grammar gives rise to ので.

Because I didn’t feel good I took a break from work.

Literally: “By means of the thing that is not feeling good I took a break from work”.

Although the above is grammatically correct you would not likely hear it in conversation. Instead こと would be replaced with の to make a more natural sentence.

I didn’t feel good so I took a break from work.
The washing machine broke so I went to buy a new one.

Note how の is used to avoid repeating “washing machine”. It’s obvious from the context that you’re not going to go and buy a new toaster so the word “washing machine” doesn’t need to be repeated (in the same way I use “one” in the translation). の really is the lexical joker!

の may also be shortened to ん when used to mean ので in conversation.

I have an exam tomorrow so I’ll get to bed early today.

Like its counterpart から, ので can append itself to both the standard and polite forms of verbs and adjectives.

I’ve got a lot of luggage so I’ll go by car not train.
I’ve got two televisions so I’m going to sell one.

However, unlike から we cannot use ので in reply to a question.

MikeWhy are you tired?
YukikoBecause yesterday I was working until 11pm.
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