In an occupancy grid map generation device for generating an occupancy grid map that indicates, for each of cells of a grid into which a region is divided, an occupancy probability that an object occupies the cell, an occupancy probability updating unit is configured to, based detection result data of an object therearound, successively update the occupancy probability for each of the cells calculated at a previous time to calculate a latest occupancy probability. An updating weight calculation unit is configured to acquire data about presence or absence of an object in each of the cells therearound based on map data, and determine a weight of the detection result data used by the occupancy probability updating unit to update the occupancy probability for the cell, based on a degree of match between the data about presence or absence of an object in the cell and the detection result data.