A power output apparatus (20) of the present invention includes an engine (50), a clutch motor (30) connecting with crankshaft(56), an assist motor (40) connecting with a drive shaft (22), and a controller (80) for controlling the clutch motor (30) and the assist motor (40). When an electrical angle of rotors in the clutch motor (30) is equal to π/2, a constant current is made to flow through three-phase coils (36) of the clutch motor (30) in order to enable a torque equal to or greater than a maximum torque ripple of the engine (50) to be applied from the clutch motor (30) to a drive shaft (22) and the crankshaft (56). This locks up an outer rotor (32) and an inner rotor (34) of the clutch motor (30). This structure enables the torque and rotation of the engine (50) to be directly transmitted to the drive shaft (22) at a high efficiency.