Abstract: A power on/off circuit with a lock function includes a momentary type main switch connected to ground, a two-circuit two-contact lock switch coupled to, a switching state holding circuit, a load and a power supply. One of the switching circuits in the lock switch is connected between the main switch and the input terminal (CK) of the switching state holding circuit. The other switching circuit in the lock switch is connected between the main switch and the reset terminal (CLR) of the switching state holding circuit. The switching state of the main switch is held by the switching state holding circuit, and the state is maintained unless a reset signal is applied to the switching state holding circuit. The lock switch only functions to generate the reset signal so that the lock switch does not cut off the supply of current to the load as in a conventional shaver.