an image information calculation unit configured to extract each of image feature points from a plurality of images which are sequentially captured from a specified spot by an image capturing unit mounted in the mobile object and associate the image feature points with each other between the plurality of images;

a travel amount calculation unit configured to estimate the position of the mobile object by calculating a travel amount of the mobile object from the specified spot on the basis of information about movements of the mobile object;

a three-dimensional image feature point calculation unit configured to estimate a three-dimensional position of the image feature point in a real space on the basis of a result of associating the image feature points with each other between the plurality of images and the position of the mobile object estimated by the travel amount calculation unit;

a position-in-route judgment unit configured to judge whether or not the position of the mobile object which is estimated by the travel amount calculation unit has reached a preset relay spot on the route, the preset relay spot is set on the preset route which is provided to the position estimation apparatus by an automatic parking system;

a position correction unit configured to calculate a position error between a position of the three-dimensional position estimated from an image captured by the image capturing unit, the position of the three-dimensional position being in the relevant image when the three-dimensional position is reprojected onto the relevant image, and the image feature point extracted from the relevant image when the position in-route judgement unit determines that the position of the mobile object has reached the preset relay spot, and correct the position and posture of the mobile object so as to reduce the position error; and

a route regeneration judgment unit configured to calculate differences between the position and posture of the mobile object corrected by the position correction unit and a position and posture of the mobile object which are preset with respect to the preset relay spot, and determine to regenerate the route if at least one of the calculated respective differences is equal to or larger than one of threshold values and determine not to regenerate the route if the calculated respective differences are not equal to or larger than the threshold values,

wherein the preset relay spot is a steering-wheel-turning spot for the mobile object to switch from a forward movement to a reverse movement or from the reverse movement to the forward movement on the route and the route is a parking route to a designated parking position.