A power generating unit consists of an internal combustion engine (1) and a generator (2), the former comprising a crankshaft (8) received in a crankcase (5) and the generator comprising a generator housing (20) connected to the crankcase (5), a stator (36) and a rotor (30) that is connected so as to rotate with the crankshaft (8). The aim is to provide a power generation unit that requires little space and that allows a precise guidance of a rotor designed for the overall unit power. A concentric stub shaft (11) is fixedly connected at the one end to the crankshaft (8) and at the other end to the rotor (30). The generator housing (20), on its side facing the internal combustion engine (1), has a front plate (21) that accommodates a bearing (23) for the sub shaft (11). The rotor (30) is otherwise overhung.