1. A road estimation device configured to receive data including a core point from an external object, the core point being assigned along a road and being assigned with attributes for identifying the road, the road estimation device further configured to extract a link pertinent to the road represented by the core point for estimating the road on a map, the road estimation device comprising: a map data input unit configured to input map data including links having attributes corresponding to the attributes of the core point; a link extraction unit configured to extract a candidate link being candidate of the road represented by the core point from the map data according to the attribute of the link and the attributes of the core point, wherein the link extraction unit is further configured to: first implement a non-shape-relevant narrowing-down processing to narrow down links into candidate links, each of which has an attribute corresponding to a non-shape-relevant attribute of the attributes of the core point, according to the non-shape-relevant attribute being irrelevant to a road shape; and subsequently implement a shape-relevant narrowing-down processing to narrow down the candidate links into a candidate link, which has an attribute corresponding to a shape-relevant attribute of the attributes of the core point, according to the shape-relevant attribute being relevant to the road shape.