The present application relates to correction of position data used in a position information collection system, in which measurement points correspond to position data of a mobile body at respective time points and a movement path of the mobile body connects the measurement points in a time series. When the position data produces a movement path of the mobile body which passes through a not-enterable area, the position data is corrected such that the movement path of the mobile body circumvents the not-enterable area without reducing positioning accuracy, by performing position correction operations which include: determining a crossing status with regard to how the movement path crosses the not-enterable area; counting a number of the measurement points within the not-enterable area; and correcting the position data such that the movement path circumvents the not-enterable area.