To provide a small and inexpensive servo controller having a ground fault detection function.

This servo controller, consisting of: a converter section 3 for rectifying an AC power supply and generating a DC power supply; and a plurality of inverter sections 5 for generating a drive power supply for a motor from the DC power supply, includes: a power supply breaker 2 connected to AC power supply side of the converter section 3; and a ground fault detection circuit 16 built in the converter section 3. With this constitution, if a ground fault occurs, operation of all the inverter sections 5 is stopped to shut down the breaker 2.