A position estimation system estimates a position of a mobile unit including a camera that captures an image of an area around the mobile unit. The system includes an ECU configured to store a plurality of pieces of map information, the plurality of pieces of map information respectively including a plurality of pieces of image information and respectively including a plurality of pieces of first positional information. The image information corresponding to a plurality of images respectively captured at a plurality of points within a predetermined range, the first positional information being acquired based on information other than the image information and respectively corresponding to the points, environmental conditions of the map information when the images were captured are different from each other, acquire an image captured by the camera, and estimate the position of the mobile unit based on the image acquired by the ECU and the map information.