A ship monitoring device, comprising: a display unit for displaying, on the basis of information on own ship navigating on the sea and information on a target ship alongside, animation of a position of the own ship and a position of the target ship alongside to display a state in which the own ship and the target ship alongside come alongside each other; a sensed information communication unit including a specified low power radio for receiving internal air pressure information as sensed information in form of packet data, the internal air pressure information being transmitted from specified low power radios provided in a plurality of fenders, respectively, the plurality of fenders being provided in the own ship and serving as a cushioning material that is disposed between the own ship and the target ship alongside in a case where the own ship and the target ship alongside come alongside each other; and means for transmitting information on own ship, the means including a specified low power radio for transmitting the information on own ship in form of packet data to the target ship alongside, the information on own ship being one or more kinds of information including, as one kind of the information, the sensed information contained in the packet data received by the sensed information communication unit, wherein, in the ship monitoring device in which one kind of the packet data transmitted from the plurality of fenders comprises the sensed information being arranged between a start control code and a termination control code, and the packet data transmitted from the means for transmitting information on own ship comprises the information on own ship being arranged between two consecutive start control codes and two consecutive termination control codes, and type information indicating an information type of the information on own ship, the type information being arranged between the information on own ship and the two consecutive start control codes and between the two consecutive termination control codes and the information on own ship a display unit for displaying, on the basis of information on own ship navigating on the sea and information on a target ship alongside, animation of a position of the own ship and a position of the target ship alongside to display a state in which the own ship and the target ship alongside come alongside each other; a sensed information communication unit including a specified low power radio for receiving internal air pressure information as sensed information in form of packet data, the internal air pressure information being transmitted from specified low power radios provided in a plurality of fenders, respectively, the plurality of fenders being provided in the own ship and serving as a cushioning material that is disposed between the own ship and the target ship alongside in a case where the own ship and the target ship alongside come alongside each other; and means for transmitting information on own ship, the means including a specified low power radio for transmitting the information on own ship in form of packet data to the target ship alongside, the information on own ship being one or more kinds of information including, as one kind of the information, the sensed information contained in the packet data received by the sensed information communication unit, wherein, in the ship monitoring device in which one kind of the packet data transmitted from the plurality of fenders comprises the sensed information being arranged between a start control code and a termination control code, and the packet data transmitted from the means for transmitting information on own ship comprises the information on own ship being arranged between two consecutive start control codes and two consecutive termination control codes, and type information indicating an information type of the information on own ship, the type information being arranged between the information on own ship and the two consecutive start control codes and between the two consecutive termination control codes and the information on own ship