An electronic device has a temperature sensor that detects temperature of a CPU, an image processing unit, and a microprocessor unit that controls the supply of electric power from a power source unit to the CPU and the image processing unit according to the temperature detected by the temperature sensor. If the temperature of the CPU and/or the image processing unit is detected by the temperature sensor to be near the temperature that causes malfunction or damage to them, the supply of electric power to the CPU and the image processing unit is automatically stopped by the microprocessor unit. It is possible to prevent malfunction and damage of the CPU and the image processing unit and to easily prevent the occurrence of runaway programs, etc.