Clutch device and motor apparatus having the same

In a clutch device (10), an output shaft (12) supports an input disk (28) rotatably about an axis thereof, and a clutch disk (38) non-rotatably about the axis and movably in an axial direction of the output shaft (12). An elastic member (44) exerts resistive force on the input disk (28) or the clutch disk (38) when the clutch disk (38) is about to come out of an engagement with the input disk (28). One of the input disk (28) and the clutch disk (38) has a trailing surface (51) inclined by a predetermined angle from the axis, and the other has a curved control surface (53) to come in a line contact with the trailing surface (51) in a circumferential direction of the output shaft (12). The trailing surface (51) and the curved control surface (53) generate a component force of a driving force in the axial direction. The other having the curved control surface (53) is higher in hardness than the one having the trailing surface (51).