SHIP NAVIGATION ASSISTANCE DEVICE

A ship navigation assisting device includes: an area setter 304 that sets, for a target ship, a polygonal safe navigation area defined by a plurality of vertices and surrounding the target ship; a collision point calculator 305 that calculates, based on a speed of the own ship, a relative position between the own ship and the target ship, and a velocity vector of the target ship, collision points between each of the plurality of vertices constituting the safe navigation area and the own ship; and a collision danger area calculator 306 that connects the plurality of collision points calculated by the collision point calculator 305 to calculate a collision danger area.