A power supply device of the present invention includes an electric double layer capacitor connected to, e.g., an HDD (Hard Disk Drive), CD-ROM (Compact Disk Read Only Memory) drive, floppy disk drive or similar motor-driven equipment, and another electric double layer capacitor connected to, e.g., a pulse generating device included in a radio transmitter. The capacitors each feed power when the load of the associated equipment sharply varies during operation of the equipment. This makes it needless for a main power supply to feed such power. A laminate polymer battery is connected to a low voltage IC (Integrated Circuit) and feeds power thereto. This also makes it needless for the main power to feed power to the low voltage IC, and allows a short feed line to connect the laminate polymer battery and IC. The short feed line reduces the transfer of noise to the IC and therefore malfunction ascribable to noise.