Abstract: A clutch device includes: an input disk; an output disk; and a biasing member configured to press the input disk and the output disk against each other, the input disk and the output disk contact or separate from each other in an axial direction, and at opposing surfaces thereof, respectively have tooth portions engageable with or disengageable from each other, at each tooth portion, recessed and raised portions extending in a radial direction are alternately provided in a circumferential direction, each of the recessed and raised portions is formed so that a width in the circumferential direction may outwardly expands in the radial direction, and engagement force in the axial direction is greater on an inside of the tooth portions in the radial direction than on the outside when the tooth portions of the input disk and the output disk pressed by the biasing member are fitted in each other.

Abstract: To provide an SmCo-based rare earth sintered magnet having a small diameter and a multipolar magnetized magnetic structure and having a high coercive force and a high magnetization rate. The outer shape of an SmCo-based rare earth sintered magnet having a coercive force HCJ (kOe) at a room temperature (° C.) of 7.5 (kOe)<HCJ?27 (kOe) is formed into any one of a cylindrical shape, a ring-like shape, a columnar shape, and a disk-like shape. Multi-pole magnetization is performed on the SmCo-based rare earth sintered magnet so as to satisfy (diameter D/the number of poles p) (mm)<(4/?) (mm) (p is an even number equal to or greater than 4), and the magnetization rate is set to 80(%) or more.