According to one embodiment, a base station includes a licensed band transmitting unit, a determining unit, and an unlicensed band transmitting unit. The licensed band transmitting unit transmits, to a terminal, a control signal for specifying a resource in a shared band to be used for data transmission by the terminal. The determining unit determines whether the resource in the shared band is idle or busy. The unlicensed band transmitting unit transmits a permission signal for permitting transmission in the shared band when the determining unit determines that the resource in the shared band is idle. The control signal or the permission signal includes an offset indicating a time from the permission signal to a start of transmission of data from the terminal to the base station with reference to the permission signal transmitted from the unlicensed band transmitting unit.