Often, questions written in Japanese end in a full stop, not a question mark. But why?
When not to use a question mark
If a question ends in the question marker ka (か), it doesn't need a question mark, because the 'ka' tells us that this is a question:
Ima nanji desu ka.
What time is it?
That doesn't mean you can't use a question mark with か. People do it, especially in casual contexts. You just don't need to (and you shouldn't in formal writing).
Here's a question with か and a question mark, from the McDonald’s Japan website:
Hambaagaa wa nagai aida houchi shitemo kusaranai to kikimashita. Hontou desu ka?
I heard you can leave a hamburger for a long time and it won't go bad. Is that true?
Adding a question mark after か here makes 本当ですか？ sound a bit more casual, friendly and questioning.
When to use a question mark
In questions without ka, question marks are pretty common:
How about tomorrow?
What's your job?
Gakkou ni itta?
You went to school?
Without a question mark, these short written statements wouldn't obviously be questions.
That's all from me for today. So... any questions?
First published December 11, 2015
Updated December 13, 2018