A power transmission apparatus is used in a vehicle and mounted on a vehicle member via a mount. The power transmission apparatus includes a case. The case includes a motor provided inside the case. The case includes a mount fastening portion for fastening the mount with a plurality of bolts. The mount fastening portion has a plurality of bolt tightening holes. The plurality of bolt tightening holes are provided so that the plurality of bolts are tightened into the plurality of bolt tightening holes. The bolt tightening holes have axial directions parallel to each other. A space isolated from an inside of the case is formed by a wall of the case in a region connecting two adjacent bolt tightening holes when the mount fastening portion is viewed in the axial directions of the plurality of bolt tightening holes.