Valve timing adjustment device

A valve timing adjustment device configured to adjust an opening/closing timing of a valve of an engine by rotation of a cam shaft driven by a motor, comprising:

• a speed reduction mechanism that includes
• a rolling bearing arranged between the motor and the cam shaft,
• an oiling passage through which lubricating oil is supplied to the rolling bearing, and
• a thrust receiver configured to lock the rolling bearing at a predetermined position in an axial direction, wherein
• the rolling bearing includes a raceway groove to guide a rolling element at a surface of an inner ring and a surface of an outer ring opposed to each other,
• the raceway groove includes a deep groove provided at one side with respect to a center of the rolling element in the axial direction, and a shallow groove that is shallower than the deep groove and provided at the other side with respect to the center of the rolling element in the axial direction, and
• the thrust receiver includes a first draining portion to discharge the lubricating oil to outside of the rolling bearing from the shallow groove of the outer ring.