A marine vessel propulsion system includes multiple propulsion devices, multiple operation levers, and multiple lever position sensors arranged to detect the positions of the multiple operation levers, and a control unit. The control unit is programmed to control, based on detection results from the multiple lever position sensors, the shift states of the respective propulsion devices and to change the steering angle of at least one of the propulsion devices. The control unit may be arranged to change the steering angles of the propulsion devices to facilitate the behavior of the hull corresponding to the shift states of the respective propulsion devices.