Provided is a magnetic power transmission device capable of improving the power transmission efficiency and transmission capability while maintaining the merits obtained when performing power transmission by using a magnetic force and reducing the manufacturing cost. The magnetic power transmission device (1) includes: an external rotor (11) having a plurality of left and right permanent magnets (11c) arranged in the circumferential direction; an internal rotor (12) having a plurality of permanent magnets (12c) arranged in the circumferential direction; and an intermediate rotor (13) having a plurality of left and right soft magnetic bodies (13d, 13e) arranged in the circumferential direction. When the left and the right permanent magnets (11c) are positioned to oppose to the permanent magnets (12c): if the left permanent magnet (11c) has a polarity different from that of the left side of the permanent magnet (12c), the right permanent magnet (11c) has a polarity identical to that of the right side of the permanent magnet (12c); and if one of the soft magnetic bodies (13d, 13e) is positioned between the permanent magnets (11c, 12c), the other is positioned between the two adjacent permanent magnets (11c, 12c).