The utility model discloses a motor safety switch, which comprises a key, a lock core, a lock shell, a spring, a copper sheet and a cover plate. the center of the front end surface of the lock shell is provided with a long hole; middle parts of the two side edges of the long hole have symmetrical arc-shaped structures; the symmetrical arc-shaped structures of the middle parts at two side edges of the long hole are matched with the symmetrical grooves in the middle part of the key; a limiting block at the front end surface of the lock shell can enable the key to be limited to rotate within the range of 0DEG to 90 DEG; the center of the rear end surface of the lock core is provided with a blind hole; the spring is located in the blind hole; two short edges of the copper sheet are respectively provided with limiting claws; the two limiting claws are respectively located in limiting grooves arranged on the outer surface of the rear end part of the lock core; the spring ejects against the middle part of the copper sheet; the inner end surface of the cover plate is provided with two electrodes; the outer end surface of the cover plate is provided with two wiring seats; the lock core is located inside the lock shell; the front end surface of the lock core is provided with a groove opening opposite to the long hole arranged in the front end surface of the lock shell; two ends of the copper sheet located on the rear end surface of the lock core eject against two bosses arranged on the inner end surface of the cover plate respectively; and the cover plate is arranged at the rear end of the lock shell.