An in-wheel motor drive unit (11) includes: a motor portion (11A) that is placed on one side in the direction of the axis of the in-wheel motor drive unit; a wheel hub portion (11C) that is placed on the other side in the direction of the axis of the in-wheel motor drive unit; a speed reduction portion (11B) that is placed between the motor portion and the wheel hub portion and that reduces the speed of output rotation of the motor portion to transmit the resultant output rotation to the wheel hub portion; and a first arm portion (34) that is formed integrally with a speed reduction portion casing (33) forming the outer shape of the speed reduction portion, that projects in a direction perpendicular to the axis from the speed reduction portion casing, and that has its tip end pivotally coupled to a vehicle body-side member.