To provide a lens block to be used for cutting a perform of a rod lens capable of improving efficiency of manufacturing, and also increasing process yielding by high precision cutting.

The cutting method is that, in a state of a lens block 11 keeping a plurality of rod lens preforms, laser lights A, B are cast toward side surfaces 19, 20, reflected light 36, 37 are received by screens 38, 39, and after the adjustments of perpendicularity of the side faces 19, 20 to a cutting plane 30 so that the reflected light 36, 37 are incident on reference lines 38a, 39a on the screen 38, 39, are finished, a cutter 30 cuts the lens block 11. The perpendicularity of an optical axis of each rod lens perform 12 to the cutting plane 33 can be set in high precision and easily.