Driving Support Method and Driving Support Device

A driving support method including: detecting a first boundary point group including boundary points forming a lane boundary line, using a sensor mounted on a vehicle; converting a coordinate system of the first boundary point group to the same coordinate system as a coordinate system of map data; and performing matching between a first point group constituted by boundary points not close to each other in either one of a second boundary point group including boundary points forming a lane boundary line in the map data and the first boundary point group and the other of the first boundary point group and the second boundary point group.