Provided is an electric drive device in which heat-dissipating sections (15A) (15B) that transfer at least heat generated by a power supply circuit unit (17) and power conversion circuit units (16) to a motor housing (11) are formed on an end surface section (15) of the motor housing (11) on the opposite side from an output section of a rotating shaft (23) of an electric motor. In addition, a watertight lid member (35) that covers a through hole (41) through which the rotating shaft passes and the end of the rotating shaft (23) from the exterior is attached to the end surface section (15) around the through hole (41), and a waterproof breathable membrane (44) that prevents the passage of moisture while allowing the passage of air and water vapor is provided to part of the watertight lid member.