A torque transmission device comprising: a magnetic pole rotating body having magnetic poles arranged in a row on a circumference thereof; a yoke rotating body configured to rotate about the same center axis of rotation as the magnetic pole rotating body and including tooth-shaped portions arranged in a row so as to oppose the magnetic poles; a side magnetic body formed of a magnetic material provided on the side of the tooth-shaped portions of the yoke rotating body; and the magnetic pole rotating body and the yoke rotating body are supported so as to be rotatable about the direction of center axis of rotation and so as to allow the magnetic poles and the side magnetic body to be relatively movable in the direction toward and away from each other along the center axis of rotation, characterized in that when a load torque exceeding a transmission torque transmissible by a magnetic attracting force that is applied between the magnetic pole rotating body and the yoke rotating body is applied between the both, the both rotating bodies relatively rotate and a coupling force applied between the opposed magnetic poles and the tooth-shaped portions is weakened, so that a component force in the direction of the axis of rotation of the magnetic attracting force applied between the magnetic poles and the side magnetic body becomes greater than a component force in the direction of axis of rotation of the magnetic attracting force applied to the magnetic pole rotating body and the tooth-shaped portion, and the magnetic poles move relatively to the positions closer to the side magnetic body along the center axis of rotation. a magnetic pole rotating body having magnetic poles arranged in a row on a circumference thereof; a yoke rotating body configured to rotate about the same center axis of rotation as the magnetic pole rotating body and including tooth-shaped portions arranged in a row so as to oppose the magnetic poles; a side magnetic body formed of a magnetic material provided on the side of the tooth-shaped portions of the yoke rotating body; and the magnetic pole rotating body and the yoke rotating body are supported so as to be rotatable about the direction of center axis of rotation and so as to allow the magnetic poles and the side magnetic body to be relatively movable in the direction toward and away from each other along the center axis of rotation, characterized in that when a load torque exceeding a transmission torque transmissible by a magnetic attracting force that is applied between the magnetic pole rotating body and the yoke rotating body is applied between the both, the both rotating bodies relatively rotate and a coupling force applied between the opposed magnetic poles and the tooth-shaped portions is weakened, so that a component force in the direction of the axis of rotation of the magnetic attracting force applied between the magnetic poles and the side magnetic body becomes greater than a component force in the direction of axis of rotation of the magnetic attracting force applied to the magnetic pole rotating body and the tooth-shaped portion, and the magnetic poles move relatively to the positions closer to the side magnetic body along the center axis of rotation.