To provide a mold for molding a free curved surface optical element capable of manufacturing the free curved surface optical element, which is stable in the relation between a free curved surface and an attaching reference surface and easy to adjust at the time of attachment, with high precision at a low cost.

The mold for molding the free curved surface optical element is constituted of a fixed mold and a movable mold both of which mold the free curved surface (effective region 21) and the back face on its opposite side by the parting line PL provided along the edge face of the free curved surface optical element 14. The molding surface for forming the free curved surface (effective region 21) and the molding surface, which forms axial direction attaching reference surfaces 28a-28c for attaching the free curved surface optical element 14 in the direction right-angled to the free curved surface (effective region 21), are arranged to the mold on the same side with respect to the parting line PL.