A safety system has higher user design flexibility. Motor controllers (20, 30) include a motor drive circuit (207) that outputs a motor voltage command signal for driving motors (90, 100) in accordance with a motor drive command value, an inverter (211) that supplies power for driving the motors (90, 100) by switching based on the motor voltage command signal, a safety control unit that outputs a drive permission signal for driving the motors (90, 100) in accordance with communication data received through a communication circuit (213), a cut-off circuit (209) that receives the drive permission signal and the voltage drive command signal and cuts off the voltage drive command signal to an inverter (211) when receiving no drive permission signal, and a safety input unit (205) that receives redundant safety input signals. The cut-off circuit (207) receives a logical AND of the safety input signal and the drive permission signal.