He was the principal bomb maker of the Jugantar group[1] until Hemchandra Kanungo returned from Paris learning political theory and explosive chemistry.

Ullaskar was born on 16 April 1885 to a Bengali Baidya family in the village of Kalikachha, Sarail, then located under the Brahmanbaria subdivision of the Bengal Province's Tipperah District (present-day Bangladesh).

Khudiram Bose used a bomb manufactured by Ullaskar and Hem Chandra Das[3] in an attempt to murder the notorious magistrate, Kingsford.

However, police caught many members of the Jugantar group including Ullaskar Dutta, Barindra Ghosh and Khudiram.

Ullaskar was subjected to brutal torture and repeated electrocution in the Cellular Jail and is said have lost his mental balance.