To provide a compact clutch and brake device capable of quickly starting and stopping a working means such as a cutting blade.

This clutch and brake device 20 comprises an input hub 23 fitted to a driving shaft 14, an output hub 50 to be relatively rotated with the driving shaft 14 at a tip 23a of the input hub 23 and connected to a cutting blade 16, a friction plate 60 arranged between the output hub 50 and the input hub 23 and to be moved on the axis of the driving shaft 14, a brake plate 42 for connecting and disconnecting the friction plate 60 and the input hub 23 to/from each other and for stopping the rotation of the friction plate 60, and a disk spring 70 arranged between the friction plate 60 and the output hub 23 and for energizing the friction plate 60 toward the brake plate 42. Engaging claws 71, etc., of the inner peripheral side of the disk spring 70 are engaged with grooves 52, etc., of the output hub 50, and engaging grooves 73, etc., of the outer end are engaged with claws 63, etc., of the friction plate 60.