A top district police officer said the crude bombs were seized from a house in Bagdapara area under Nanoor police station limits.
The bombs were kept in five plastic containers in the deserted house.
There was no arrest during the raid which was carried following a tip off, the officer said.
Birbhum had witnessed turf battle between the ruling Trinamool Congress and opposition BJP since last year's lok sabha polls with some pockets having CPI(M) influences.