For which particular branch you are looking in National Insurance Company you did not mention, so to help you I will tell simple procedure.

To search branches please have a glance on process

Went to official site of National Insurance Company which looks like this

National Insurance Company




Site page will open at top right hand side page
You can see section of offices
Click on that section a new page will open
Which looks like this there you can search easily

National Insurance Company offices




Address:-
National Insurance Company
3, Middleton Street, Prafulla Chandra Sen Sarani , Kolkata, West Bengal, 700071.

Phone:-
22831705