An in-wheel motor drive device includes: a wheel hub bearing portion having an inner ring integrally rotating with a wheel, an outer ring facing the inner ring via a radial gap, and a hub attachment arranged on a more outer diameter side than the outer ring and mounted and fixed to the outer ring; a motor portion driving the inner ring; a casing housing a rotation transmission path from a motor rotation shaft of the motor portion to the inner ring; a suspending bracket having an upper joining seat portion joinable with an upper side suspension member of a suspension device, a lower joining seat portion joinable with a lower side suspension member of the suspension device, and an intermediate portion connecting the upper joining seat portion and the lower joining seat portion; and fixing means for mounting and fixing the suspending bracket to the hub attachment.