1. An environment, recognition device comprising: a data retaining unit that retains shape information that is information on a shape of a specific object; an edge extracting unit that obtains a luminance of each of target portions, formed by dividing a detection area of a luminance image, and extracts a target portion forming an edge; a position information obtaining unit that obtains a relative distance of the target portion forming an edge; and a specific object determining unit that determines a specific object indicated with the shape information by performing a Hough transform on a position of the target portion forming the edge based on the shape information according to the relative distance.