A navigation apparatus (1) that detects a position of a movable body includes map data storage means (13) for storing map data; an autonomous sensor (12) that detects information on behavior of the movable body; inertial position determination means (10b) for detecting an inertial position-determination position of the movable body, by accumulating the information detected by the autonomous sensor (12) on a result of position determination performed using radio navigation; characteristic position detection means (10d) for detecting a characteristic position (31) that is the inertial position-determination position at which the movable body has exhibited a characteristic behavior; correction amount detection means (10e) for extracting positional information on a road position (22) corresponding to the characteristic position (31), by referring to the map data storage means (13); and position correction means (10f) for correcting the characteristic position (31) using a Kalman filter based on a condition that the characteristic position (31) is close to the road position (22).