A hybrid drive system for outputting the power of an internal combustion engine (900) and the power of a motor generator (68) through a transmission. The transmission includes an input shaft (14) and an output shaft (39). The motor generator (68) is arranged to have an input/output motor shaft (74) in parallel with the input shaft (14) and the output shaft (39). The internal combustion engine is arranged to have its output crankshaft on the same axis as that of the input shaft (14).
