A steering device can include a steering wheel, connecting members for connecting outboard motors together, and a plurality of steering motors for steering a plurality of outboard motors. A target steering angle setting device can be configured to obtain a steering angle according to a steering displacement of the steering wheel, and steering unit angle sensor can be configured to detect actual steering unit angles of the respective outboard motors. A correcting device can be configured to obtain the difference between actual steering unit angles of the outboard motors, to correct the target steering angles based on the difference, and to obtain a target steering angle of each of the outboard motors. Motor controlling device can be configured to control the steering motors so that a target steering angle agrees with the actual steering unit angle for each of the outboard motors.