A current position determining device, comprising: current position detection means configured for detecting a current position of an own vehicle; storage means storing: map information including road configuration information identifying a configuration of a road, and road type information identifying a type of the road; and branch position information identifying a branch position of a road contained in the map information; current position estimation means configured for estimating, using the map information, an estimated current position corresponding to the current position of the own vehicle detected by the current position detection means; detection range identification means configured for identifying, based on information on a road at a branch position, a range for detecting a traveling direction of the own vehicle, as a detection range; lane change detection means configured for detecting, as long as the estimated current position of the own vehicle detected by the current position estimation means is included in the detection range identified by the detection range identification means, whether the own vehicle has changed lanes; estimated current position correction means configured for correcting the estimated current position estimated by the current position estimation means, using the information on the lane change detected by the lane change detection means; and characterized by road type determination means configured for determining, based on the estimated current position estimated by the current position estimation means and the road type information stored in the storage means, a road type of a road to which the estimated current position belongs, wherein the detection range identification means are adapted to identify the detection range according to the road type determined by the road type determination means. current position detection means configured for detecting a current position of an own vehicle; storage means storing: map information including road configuration information identifying a configuration of a road, and road type information identifying a type of the road; and branch position information identifying a branch position of a road contained in the map information; map information including road configuration information identifying a configuration of a road, and road type information identifying a type of the road; and branch position information identifying a branch position of a road contained in the map information; current position estimation means configured for estimating, using the map information, an estimated current position corresponding to the current position of the own vehicle detected by the current position detection means; detection range identification means configured for identifying, based on information on a road at a branch position, a range for detecting a traveling direction of the own vehicle, as a detection range; lane change detection means configured for detecting, as long as the estimated current position of the own vehicle detected by the current position estimation means is included in the detection range identified by the detection range identification means, whether the own vehicle has changed lanes; estimated current position correction means configured for correcting the estimated current position estimated by the current position estimation means, using the information on the lane change detected by the lane change detection means; and characterized by road type determination means configured for determining, based on the estimated current position estimated by the current position estimation means and the road type information stored in the storage means, a road type of a road to which the estimated current position belongs, wherein the detection range identification means are adapted to identify the detection range according to the road type determined by the road type determination means.