A marine vessel propulsion apparatus includes a transom bracket, a steering shaft, an outboard motor, a tilt mechanism, and a steering mechanism. The steering shaft is joined to the transom bracket, and is turnable around a steering axis extending in an up-down direction. The outboard motor is joined to the steering shaft, turnable around a tilt axis, and turnable around the steering axis together with the steering shaft. The tilt mechanism is arranged to turn the outboard motor around the tilt axis with respect to the steering shaft. The steering mechanism includes a power conversion mechanism arranged to convert power of the electric motor into turning of the steering shaft around the steering axis.