A discharge circuit for a power supply circuit for a motor is configured to discharge a capacitor provided in the power supply circuit. The discharge circuit includes a first voltage detector detecting a voltage inputted to a primary side of the power supply circuit, a second voltage detector detecting a voltage on the secondary side, and a discharge resistance provided in parallel with the power supply circuit on the secondary side of the power supply circuit. A power supply control means performs discharge control when a voltage detected by the second voltage detector exceeds a regenerative determination value and, in a case that a voltage on the primary side detected by the first voltage detector becomes lower than a power failure determination value, the power supply control means performs the discharge control after a lapse of a time period required for a stop operation of the industrial robot.

A discharge circuit for a power supply circuit for a motor is configured to discharge a capacitor provided in the power supply circuit. The discharge circuit includes a first voltage detector detecting a voltage inputted to a primary side of the power supply circuit, a second voltage detector detecting a voltage on the secondary side, and a discharge resistance provided in parallel with the power supply circuit on the secondary side of the power supply circuit. A power supply control means performs discharge control when a voltage detected by the second voltage detector exceeds a regenerative determination value and, in a case that a voltage on the primary side detected by the first voltage detector becomes lower than a power failure determination value, the power supply control means performs the discharge control after a lapse of a time period required for a stop operation of the industrial robot.