A mobile telephone is provided that includes a plurality of circuit blocks and adapted to cut off the supply of power source voltage to any one of the circuit blocks. The mobile telephone also includes an interblock interface circuit provided on a signal path between an elected circuit block and a branch point at which the signal path branches into different branch paths so as to connect to other circuit blocks. The interblock interface circuit includes a signal gate for preventing signal transmission from the elected circuit block to the other circuit blocks, and includes a storage unit for storing a signal right before the power cut-off.