A field effect transistor (FET)is turned ON with supply of a power Vcc to a sensor started, and a signal indicating a result of detection is inputted from the sensor to a GPI terminal of a microcomputer control unit (MCU). After supply of the power Vcc to the sensor is started, the MCU enters the sleep state, and the state is maintained until a normal detection result is outputted from the sensor. When the sensor starts outputting a normal detection result, the MCU returned from the sleep state upon an interruption by a timer, and sampling is made for an output from the sensor. When sampling is performed, supply of the power Vcc to the sensor is stopped with the CMU set in the sleep state. The present invention can be applied to a portable type of information processing apparatus such as a mobile telephone and a PDA.