A power unit includes: a differential gear (21) in which a first rotating element (21r) is connected to an output shaft of a prime mover (2), a second rotating element (21s) is connected to a body of rotation of a rotary actuator (3), and a third rotating element (21c) is connected to a driven unit (4) via a first power transmission path (22); a first power transmission system (34, 36, 37) selectively operable between an operating state for enabling power transmission in the first power transmission path (22) and an operating state for disconnecting the power transmission; a second power transmission path (23) connecting between the output shaft of the prime mover (2) and the driven unit (4); and a second power transmission system (32) selectively operable between an operating state for enabling power transmission in the second power transmission path and an operating state for disconnecting the power transmission, wherein an auxiliary device (5) is connected to one of the second rotating element (21s) and the third rotating element (21c) of the differential gear (21).