Power consumption can be reduced, and an operating time can be extended in an operation mode having lower fluctuation in power consumption in equipment having a plurality of operation modes of different power consumption. In the digital camera which also functions as an audio recorder and an audio player, it is determined whether the operation mode of the digital camera is an audio recording mode or an audio reproducing mode, or it is any other mode (shooting mode, etc.). In the audio recording mode or the audio reproducing mode, an output voltage from a power supply circuit is reduced to be lower than in the shooting mode, etc., and the threshold as a battery operation termination voltage in a battery checking process is lowered. Thus, the power consumption is reduced when the digital camera is operated as the audio recorder or the audio player, and operating time can be extended.