Light is irradiated to a light curing resin material within a mold. The light penetrates through the light curing resin material at a position off a mask. The light curing resin material gets cured at the position off the mask. The mold in this manner serves to form the contour of a molded product. On the other hand, the mask partly blocks the light. An uncured section is established in the light curing resin material behind the mask. When the light curing resin material is removed from the uncured section, the uncured section provides a hole, for example. If the mask is finely formed, it is possible to form a fine hole in an easier manner in a shorter time. It is possible to realize the mass production of a molded product having a fine hole.