Twenty-two-year-old Rafikul Islam was grievously wounded in the explosion Thursday at Bajrapara. He died at the North Bengal Medical College and Hospital at 2 a.m. Saturday.
Three others injured in the blast are still battling for life in two hospitals in northern West Bengal.
Five people died on the spot when an Improvised Explosive Device placed in a culvert went off Thursday in the Bajrangpara area, under the jurisdiction of Kotwali police station.
Kamtapur Liberation Organisation (KLO), which has been demanding a separate state from parts of northern West Bengal and Assam, was suspected to be behind the explosion.
The KLO, however, has denied involvement in the blast.