PURPOSE: To provide a design mode for a structure unit of an internal combustion engine and a generator capable of ensuring high quality level and reducing manufacturing cost.

CONSTITUTION: This is a structure unit consisting of an internal combustion engine provided with a crank chamber 1 and a crankshaft 2 for outputting torque and an electric generator/motor 3 in which a generator casing 5 thereof is firmly connected to the crank chamber 1 and a rotor 4 thereof is connected to the crankshaft 2 coaxially and in torsion-resistant manner. This structure unit is provided with an elastically deformable torque transmission plate (flex plate 6), and the disc is firmly flange-connected to an output end of the crankshaft 2. Moreover, its peripheral face is firmly connected to the rotor 4, and the rotor 4 is rotatably supported in the generator casing 5.