In an engine rotation control device, a remote control operation device is provided with a remote control side ECU and an engine side ECU so that an outboard motor can be remotely controlled. The remote control side ECU and the engine side ECU periodically communicate a control signal. A gauge includes a slow-speed operation section that changes the engine rotational speed during slow-speed cruising. The slow-speed operation section outputs a change command signal to change the engine rotational speed, and a rotational speed change signal generated by a signal output section based on the change command signal is transmitted to the engine side ECU as a periodic control signal. A reset section of the remote control side ECU resets the rotational speed change signal to an initial state in response to a request from a reset request section.