Abstract: To reduce a power loss and elongate the service life of a battery in a power supply circuit for a widely variable power-consuming load. In a device with a dry battery and a rechargeable battery, the rechargeable battery supplies the power while its output voltage is higher than a 3.4V-voltage increased voltage by a voltage increasing circuit. When the output voltage of the rechargeable battery decreases lower than 3.4V, the voltage increasing circuit operates and the dry battery works as a power supply. The power voltage increased by the voltage increasing circuit through a choke coil is fed to respective voltage decreasing circuits. The current is also fed to recharge the rechargeable battery when the output voltage of the choke coil is higher than the output voltage of the rechargeable battery. When the load is increased by the operation of a pickup, the power stored in the rechargeable battery together with the power from the dry battery after increased to 3.