A controller of a robot includes: a voltage detecting portion that detects a power-source voltage input from a power source; and a determining portion that determines, on the basis of the power-source voltage detected by the voltage detecting portion, whether to perform power-outage processing that guarantees the operation, wherein the determining portion includes a first timer that starts a clock at a point in time when the detected power-source voltage becomes equal to or less than a first threshold voltage that guarantees the operation and makes a determination for performing the power-outage processing in the case in which the power-source voltage does not exceed the first threshold voltage before the time measured by the first timer achieves a prescribed time that is longer than one cycle of the power-source voltage.