Mitra Institution (Main) is a heritage educational institution of Kolkata, West Bengal, teaching grades one to twelve under the West Bengal Board of Secondary Education and the West Bengal Council of Higher Secondary Education. The school premises are situated at 60-B Surya Sen Street, near Sealdah. There is a different co-educational primary and a girls school section up to class X.

The school was established by Babu Bisweswar Mitra on 5 January 1898. Initially it started with only five students. In 1901, Raja Peary Mohan Mukherjee became the first President of the school. After the recognition of University of Calcutta in 1904, the school became famous. Sir Ashutosh Mukherjee and Sir Alexander Pedlar, the then Vice Chancellor, helped the institution to grant affiliation of the university. Bipin Chandra Pal, Gopal Krishna Gokhale, Sir Bhupendra Nath Bose, Amritlal Bose visited Mitra Institution (Main) and became involved with its affairs.