To elongate a life while suppressing cost, in a power supply device for a game machine having a circuit for protecting an internal circuit when an overvoltage is applied.

The power supply device 11 for the game machine includes a power supply circuit 14 which an AC voltage from an AC power supply 12 into a DC voltage and smoothes it, and an overvoltage protection circuit 15 which turns off the contact point of a relay 15a when applied with the overvoltage, and prevents the overvoltage from flowing to the power supply circuit 14. The power supply device also includes relay power supply passages 21, 22 for using an electrolyte capacitor 14b arranged at the power supply circuit 14 without using an exclusive electrolyte capacitor for the supply of power to a relay drive circuit 15b which drives the relay 15a of the overvoltage protection circuit 15. Then, in the relay power supply passages 21, 22, there are arranged current regulation parts 23 which permit flows of currents in a direction in which a voltage is supplied to the relay drive circuit 15b from the power supply circuit 14, and block flows of currents in a direction opposed to the direction.