To improve precision by measuring the top position of a convex face of a male mold so as to cut a lens semi-finished product in accordance with this when the male mold is mounted on a lens cutting lathe.

A female mold is removed from a mold after polymerization, and a male mold 1 adhered with a lens semi-finished product 4 is mounted to a male mold fixing jig 41 of a measuring device 40 for the male mold depth. Just before the front curved side is cut, the male mold depth (D) of the male mold 1 is measured, and the central thickness (t) which is previously measured is added, so as to determine the top position 14 of the mold convex face of the male mold 1. The male mold 1 is thereafter fixed to a lens cutting lathe, and in accordance with the measured result, a cutting tool of the lens cutting lathe is in contact with the position corresponding to the lens thickness, thereby cutting the lens semi-finished product 4. The male mold 1 adhered with the lens material is removed from the lens cutting lathe, and similarly mounted to the main spindle of the lens polishing machine, so as to polish the front curved face of the lens material.