An electric power supply control circuit includes a bypass circuit connected in parallel with a semiconductor switch. Upon a control circuit being in an inactive state while a load being in a non-electrifying state or in a standby state, the bypass circuit connects a power source to the load. The bypass circuit includes a electrifying decision circuit that generates an activation signal for activating the control circuit in accordance with the load being put in an operation state. The electrifying decision circuit supplies the activation signal to the control circuit so as to turn on the semiconductor switch and allow electric power supply to the load through an electrifying line.