A route planning device that is capable of comprehending, in advance, a route clearance at a pass-through point on a planned travel route, includes a global map acquisition unit arranged to generate a global map showing an obstacle area in which an obstacle exists, an extended area generation unit arranged to generate an extended obstacle area and three extended area by extending stepwise an outline of the obstacle area contained in the global map, an integrated map generation unit arranged to generate an integrated map by superposing for integration of the extended obstacle area with the three extended areas; a movable area extraction unit arranged to extract a movable area from the integrated map and thinning the same, and a route planning unit arranged to acquire a route clearance at a sub goal according to the extended areas on the integrated map to which the sub goal on the travel route belongs, upon planning the travel route from the thinned movable area.