Triangle conical three-D angle retrodirective reflection element

To provide a triangular-pyramidal cube-corner retroreflective elements extremely superior in reflectivity at an entrance angle of 30 DEG or more, preferably 40 DEG or more. Triangular-pyramidal cube-corner retroreflective elements characterized in that when assuming the height from a bottom plane (Sx-Sx') including base edges (x,x,...) shared by two triangular-pyramidal reflective elements faced each other up to apexes (H1 and H2) of the triangular-pyramidal reflective elements as hx, the height from a bottom plane (Sy-Sy') including other base edges (y,y,...) of the triangular-pyramidal reflective elements as hy, and the height from a bottom plane (Sz-Sz) including still other base edges (z,z,...) of the triangular-pyramidal reflective elements as hz, any two of hx, hy, and hz are substantially different from each other and a mirror reflective layer is formed on surfaces of the triangular-pyramidal reflective elements.