To reduce the number of part items and to make a simply constructed deenergization operational type electromagnetic clutch and brake by only adding a permanent magnet.

In a magnet clutch device or a magnetic brake device wherein an energizing coil 7 and a outer yoke 5 are disposed on the fixed side, and a hollow shaft 1, a rotor 4 and an inner yoke 6 are disposed as the rotational members, at the magnetic gap between the outer yoke 5 on the fixed side and the inner yoke 6 on the rotation side, a permanent magnet 8A, or 8B is installed at one of the end surfaces of the magnetic gap. At the fixed side of magnetic clutch and the magnetic brake, an energizing coil 7 and an outer yoke 5 are disposed, and at the rotation side, the hollow shaft 1, the rotor 4 and the inner yoke 6 are disposed. At the magnetic gap between the fixed side outer yoke 5 and the rotation side rotor 4, a permanent magnet 8C or 8D is provided at one of the end surfaces of the magnetic gap.