PURPOSE: To provide the magnetic power transmission device, which has the simple structure and can transmit the constant power without mutual contact or disc magnets.

CONSTITUTION: At least two disc magnets 1 and 2, which are constituted by assembling a plurality of fan-shaped magnet plates formed in the fan shapes, are provided. The disc magnets 1 and 2 are constituted so that the polarities are inverted alternately along the circumferential direction. At the same time, the respective disc magnets 1 and 2 are brought close together and supported freely rotably. Furthermore, at least two or more number of poles are provided along the circumferential direction for the respective disc magnets 1 and 2. The respective disc magnets 1 and 2 are further constituted so that the rotating surfaces become parallel to each other. Also, the rotating surfaces are mutually deviated and arranged. Furthermore, the respective disc magnets 1 and 2 are also constituted so that the rotating surfaces are not become parallel.