A position detection apparatus comprises: a map information creation part that creates map information representing a position in a space including a floor surface on which at least one detection object may be disposed; a mask information creation part that creates mask information, by extracting a region of a predetermined height range within a height range from the floor surface when the detection object is disposed in the space from the map information; a specifying part that specifies partial optical image information, by removing a region corresponding to the mask information from the optical image information; and a detection part that specifies a positional relationship between the map information and the partial optical image information at a pixel level, and detects a position of the detection object in the map information based on the specified positional relationship.