A ship docking assisting apparatus for assisting docking of a ship by outputting ship information related to the ship to an assist target device (4, 8, 20), the assist target device (4, 8, 20) comprises a propulsion unit controller and/or a display, comprising: a storage device configured to store information; an imaging device configured to be mounted on the ship to be able to take an image of a docking target and the water surface which are located forward of the ship body, while the ship body is moved forward in the ship body front-rear direction (F, B) by a propulsion unit; and a ship docking assist processor configured to assist and having the function of assisting docking of the ship, including an approaching operation that is an operation of causing the ship to approach a shore at which the ship is to be docked until the ship is positioned to be parallel or perpendicular to the shore and a docking operation that is performed after the ship approaches the shore to some degree by the approaching operation, is different from the approaching operation, and is an operation to cause the ship which is parallel or perpendicular to the shore to make contact with or come very close to the shore, by: acquiring image information which is taken by the imaging device mounted on the ship while a ship body of the ship is moved forward in a ship body front-rear direction by a propulsion unit in the approaching operation and includes the docking target and the water surface, the docking target being an object which is the shore at which the ship is docked or an object in the vicinity of the shore and is used as a mark when the ship is docked; and the approaching operation and the docking operation being performed until the ship is docked; calculating at least one relative positional relation which indicates the relation in distance and direction between the ship body of the ship and the docking target, from plural sets of the image information including the docking target and the water surface, which are acquired while the ship body is moved forward in a ship body front-rear direction (F, B) by a propulsion unit which is provided in the ship body of the ship to generate propulsion force for moving the ship body; storing the at least one relative positional relation in the storage device as the ship information; and outputting, as the ship information, the at least one relative positional relation stored in the storage device to the assist target device (4, 8, 20). a storage device configured to store information; an imaging device configured to be mounted on the ship to be able to take an image of a docking target and the water surface which are located forward of the ship body, while the ship body is moved forward in the ship body front-rear direction (F, B) by a propulsion unit; and a ship docking assist processor configured to assist and having the function of assisting docking of the ship, including an approaching operation that is an operation of causing the ship to approach a shore at which the ship is to be docked until the ship is positioned to be parallel or perpendicular to the shore and a docking operation that is performed after the ship approaches the shore to some degree by the approaching operation, is different from the approaching operation, and is an operation to cause the ship which is parallel or perpendicular to the shore to make contact with or come very close to the shore, by: acquiring image information which is taken by the imaging device mounted on the ship while a ship body of the ship is moved forward in a ship body front-rear direction by a propulsion unit in the approaching operation and includes the docking target and the water surface, the docking target being an object which is the shore at which the ship is docked or an object in the vicinity of the shore and is used as a mark when the ship is docked; and the approaching operation and the docking operation being performed until the ship is docked; calculating at least one relative positional relation which indicates the relation in distance and direction between the ship body of the ship and the docking target, from plural sets of the image information including the docking target and the water surface, which are acquired while the ship body is moved forward in a ship body front-rear direction (F, B) by a propulsion unit which is provided in the ship body of the ship to generate propulsion force for moving the ship body; storing the at least one relative positional relation in the storage device as the ship information; and outputting, as the ship information, the at least one relative positional relation stored in the storage device to the assist target device (4, 8, 20).