To make a mechanism sealable by automating a clutch and a brake by mechanical internal braking without using an energization coil.

In this magnetic clutch/brake unit, a plurality of rotators 11 having magnets are provided to face each other, a slide groove is provided in an input shaft 1 at a proper inclination angle, and a movable body 7 is moved forward along the slide groove using centrifugal force to approach by attracting force of the magnets on an output shaft 12. The clutch 15 provided is connected to transmit torque. As input is stopped, the clutch is disconnected by repulsion of a compression spring 10 and force of a tension spring. The movable body 7 retracts, and a brake pad 16 provided in it is pressed to a brake lining 17 around a main body for braking. The driven side is braked by a brake provided on a drum which simultaneously cooperates with it to make mechanical action to achieve automation.