A road estimation device configured to receive data including a plurality of core points (CPa, CPb) from an external object, the core points (CPa, CPb) being assigned along a road and being respectively assigned with attributes for identifying the road, the road estimation device further configured to extract links pertinent to the road represented by the core points (CPa, CPb) for estimating the road on a map, the road estimation device comprising: a map data input unit configured to input map data of a plurality of parcels (Pa, P2, P3), each of the parcels being generated by dividing a map area and including links, the links respectively having attributes corresponding to attributes of the core points (CPa, CPb); a core point selection unit configured to, when the core points (CPa, CPb) are located crossing a boundary of an object parcel which is a parcel being indicated on a screen, select, as a processing object core point to be processed, a core point (CPa) inside the object parcel from the core points (CPa, CPb) in the map data which the map data input unit inputs; and a link extraction unit configured to extract candidate links being candidate of a road represented by the selected processing object core point or selected processing object core points from the map data according to the attributes of the links and the attribute of the selected processing object core point or selected processing object core points, characterised in that the core point selection unit is configured to select, as an additional processing object core point to be processed, an immediately-after-crossing-boundary core point (CPb) depending on one of (i) a distance from the boundary of the object parcel to an immediately-before-crossing-boundary core point (Cpa), (ii) a distance from the boundary of the object parcel to the immediately-after-crossing-boundary core point (CPb), or (iii) a comparison result of the distance from the boundary of the object parcel to an immediately-before-crossing-boundary core point (CPa) and the distance from the boundary of the object parcel to the immediately-after-crossing-boundary core point (CPb), wherein the immediately-before-crossing-boundary core point (CPa) is a core point which is located inside the object parcel immediately before the boundary of the object parcel, and the immediately-after-crossing-boundary core point (CPb) is a core point which is located outside the object parcel immediately after the boundary of the object parcel. a map data input unit configured to input map data of a plurality of parcels (Pa, P2, P3), each of the parcels being generated by dividing a map area and including links, the links respectively having attributes corresponding to attributes of the core points (CPa, CPb); a core point selection unit configured to, when the core points (CPa, CPb) are located crossing a boundary of an object parcel which is a parcel being indicated on a screen, select, as a processing object core point to be processed, a core point (CPa) inside the object parcel from the core points (CPa, CPb) in the map data which the map data input unit inputs; and when the core points (CPa, CPb) are located crossing a boundary of an object parcel which is a parcel being indicated on a screen, select, as a processing object core point to be processed, a core point (CPa) inside the object parcel from the core points (CPa, CPb) in the map data which the map data input unit inputs; and a link extraction unit configured to extract candidate links being candidate of a road represented by the selected processing object core point or selected processing object core points from the map data according to the attributes of the links and the attribute of the selected processing object core point or selected processing object core points, characterised in that the core point selection unit is configured to select, as an additional processing object core point to be processed, an immediately-after-crossing-boundary core point (CPb) depending on one of (i) a distance from the boundary of the object parcel to an immediately-before-crossing-boundary core point (Cpa), (ii) a distance from the boundary of the object parcel to the immediately-after-crossing-boundary core point (CPb), or (iii) a comparison result of the distance from the boundary of the object parcel to an immediately-before-crossing-boundary core point (CPa) and the distance from the boundary of the object parcel to the immediately-after-crossing-boundary core point (CPb), wherein the immediately-before-crossing-boundary core point (CPa) is a core point which is located inside the object parcel immediately before the boundary of the object parcel, and the immediately-after-crossing-boundary core point (CPb) is a core point which is located outside the object parcel immediately after the boundary of the object parcel.