Abstract: In a marine propulsion apparatus that transmits power of at least one of an internal combustion engine (ICE) and a generator motor (GM) mounted on a ship to a propeller via a forward reverse switching mechanism, the marine propulsion apparatus can be downsized as a whole. The marine propulsion apparatus includes a connection switching mechanism capable of selectively connecting the GM to an upstream side and a downstream side of the power transmission from the ICE in the forward reverse switching mechanism. Then, the forward reverse switching mechanism is interposed between the ICE and the connection switching mechanism, and a large torque from the ICE is not directly transmitted to the connection switching mechanism. As a result, it is not necessary to increase the capacity of the connection switching mechanism, and the connection switching mechanism and thus the marine propulsion apparatus can be downsized.