SPEED REDUCTION MECHANISM AND MOTOR ROTATIONAL FORCE TRANSMISSION DEVICE INCLUDING THE SAME

PROBLEM TO BE SOLVED: To provide a speed reduction mechanism capable of suppressing the occurrence of inclination and vibration of a rotational axis, and a motor rotational force transmission device including the same.SOLUTION: A speed reduction transmission mechanism 5 comprises: ball bearings 35, 38 for rotatably supporting a flange 30c provided integrally with a differential case 30 and a flange 30f connected to the flange 30c by a plurality of output members 53, on the outer peripheral surface of a motor shaft 42; and ball bearings 66, 67 arranged on the axis lines of the ball bearings 35, 38, and rotatably supporting the flanges 30c, 30f on the inner peripheral surface of a rotational force application member 52. In the ball bearings 66, 67 and the ball bearings 35, 38, each of the ball bearings 35, 38 and ball bearings 66, 67 is applied with an axial load as a pre-load.