POWER TRANSMISSION DEVICE

[Problem] To minimize the ingress of lubricating oil into breather holes. [0002] [Solution] This power transmission device has, inside a box, a gear mechanism, a wall section that axially overlaps the gear mechanism, and a plate provided axially between the wall section and the gear mechanism. The box is divided by the plate into a first chamber in which the gear mechanism is positioned and a second chamber having the wall section as part of a wall, and the box has breather holes in the second chamber.