According to the present invention, various biological signals can be measured at an appropriate position without depending on an expert. A biological-signal measurement device includes a sensor 1 that is in contact with a nerve fiber N and detects a nerve action potential generated in the nerve fiber N, a signal processor 2 that is connected to the sensor 1 via wiring 5, the signal processor 2 obtaining a signal based on the nerve action potential from the sensor 1 and wirelessly transmitting the obtained signal, and a receiving/transmitting unit 3 that receives the signal from the signal processor 2. The sensor 1 and the signal processor 2 are embedded in a body. The receiving/transmitting unit 3 receives the signal from the signal processor 2 via skin S.