How can I change TIMESTAMP to TIMESTAMP(3)?
I'm answering for my own question.

I found an answer solves the exact problem.

https://stackoverflow.com/a/23671577/330457 

Shortly, I needed to specify the same type for DEFAULT.

ALTER TABLE &lt;table&gt;
MODIFY COLUMN &lt;column&gt;
TIMESTAMP(3)
NOT NULL
DEFAULT CURRENT_TIMESTAMP(3) -- See?