MOBILE TERMINAL DEVICE, POWER SUPPLY SYSTEM, AND POWER SUPPLY METHOD AND POWER SUPPLY PROGRAM FOR MOBILE TERMINAL DEVICE

Portable terminal equipment capable of operating for a long time is provided. Portable terminal equipment of the present invention includes: a plurality of circuits separated galvanically and a power supply switching switch which switches power supply to the plurality of circuits between power supply from a USB (Universal Serial Bus) and power supply from a battery for each of respective circuits included in the plurality of circuits.