To provide a motor protector against overload which can simply protect a motor from overload.

An AC power source and a DC motor 1 are connected with each other through a diode 6 for preventing the reverse flow by the counter electromotive force of the DC motor 1. A diode 8 and a resistor 10 are arranged in parallel with the diode 6 and the DC motor 1, and also this protector is provided with a current detecting circuit 12 which detects the current flowing from the DC motor 1 to a resistor 10. Moreover, this is provided with a judging circuit 14 which breaks the connection between the AC power source and the DC motor 1 when the current detected by the current detecting circuit 12 has decreased. When the DC motor 1 stops by overload, the potential difference between the DC motor 1 and the resistor 10 disappears, so the current flowing from the DC motor 1 to the resistor 10 decreases, and this breaks the connection to the AC power source to protect the DC motor.