A signal processing circuit detects vibration applied to an acceleration switch. A main determination section connectable to the acceleration switch compares an output of the acceleration switch to a preset first determination criterion to determine the vibration applied to the acceleration switch. A power supply control section control supply of power based on a result of the determination made by the main determination section. A main control section controls a control target based on the power supplied from the power supply control section. A sensor detects a physical quantity applied to the sensor based on the power supplied from the power supply control section. The power supply control section controls the supply of the power to at least one of the main control section and the sensor based on the result of the determination made by the main determination section as to the vibration applied to the acceleration switch.