10 years has passed since our house was made, so it might be such a time.
And I was searching this switch. It indicates "JW-S11" "NKK", and went to some electronics stores, but could not find this switch.
This maker (NKK) has some branch including Osaka, but it is not near our house.
So I search this words with amazon and find this. Amazing !
It is about 2$ plus 6$ of sending cost. And ordered 4 days before and arrived yesterday.
And today, I fixed the light using soldering iron.
I was surprised that amazon deal with such kind of things which normal people seldom needs. Very convenient period of time !