An in-wheel motor drive device comprising: a motor unit; a wheel hub bearing unit; a speed reduction unit that reduces the rotational speed of the motor unit and transmits the reduced rotational speed to the wheel hub bearing unit; and a carrier that is linked to a vehicle body member, wherein the wheel hub bearing unit includes an outer ring disposed on an axially outer side of the wheel hub bearing and coupled to a wheel, a stationary shaft passing through a center bore of the outer ring, and a plurality of rolling elements arranged in an annular space between the outer ring and the stationary shaft, the motor unit and the speed reduction unit are disposed to offset from an axis of the wheel hub bearing unit in a direction perpendicular to the axis, the motor unit is disposed adjacent to an axially inner end portion of the stationary shaft, the speed reduction unit includes an output gear coupled to the outer ring, and a rolling bearing provided between the output gear and the stationary shaft to rotatably support the output gear, and the carrier is disposed on an axially inner side relative to the wheel hub bearing unit, and secured to the axially inner end portion of the stationary shaft, wherein the speed reduction unit includes a casing wall part that is disposed on the axially inner side relative to the wheel hub bearing unit, and is coupled to the axially inner end portion of the stationary shaft, characterized in that the stationary shaft includes a projecting portion at the axially inner end portion thereof, the projecting portion projecting radially outward relative to an axially outer end portion of the stationary shaft, and the projecting portion and the motor unit are disposed to overlap each other when viewed in the direction of the axis of the wheel hub bearing unit. a motor unit; a wheel hub bearing unit; a speed reduction unit that reduces the rotational speed of the motor unit and transmits the reduced rotational speed to the wheel hub bearing unit; and a carrier that is linked to a vehicle body member, wherein the wheel hub bearing unit includes an outer ring disposed on an axially outer side of the wheel hub bearing and coupled to a wheel, a stationary shaft passing through a center bore of the outer ring, and a plurality of rolling elements arranged in an annular space between the outer ring and the stationary shaft, the motor unit and the speed reduction unit are disposed to offset from an axis of the wheel hub bearing unit in a direction perpendicular to the axis, the motor unit is disposed adjacent to an axially inner end portion of the stationary shaft, the speed reduction unit includes an output gear coupled to the outer ring, and a rolling bearing provided between the output gear and the stationary shaft to rotatably support the output gear, and the carrier is disposed on an axially inner side relative to the wheel hub bearing unit, and secured to the axially inner end portion of the stationary shaft, wherein the speed reduction unit includes a casing wall part that is disposed on the axially inner side relative to the wheel hub bearing unit, and is coupled to the axially inner end portion of the stationary shaft, characterized in that the stationary shaft includes a projecting portion at the axially inner end portion thereof, the projecting portion projecting radially outward relative to an axially outer end portion of the stationary shaft, and the projecting portion and the motor unit are disposed to overlap each other when viewed in the direction of the axis of the wheel hub bearing unit.