PROCESSING METHOD OF OPTICAL ELEMENT AND PROCESSING METHOD OF FORMING DIE

PROBLEM TO BE SOLVED: To realize a processing of a diffraction grating element with no warp by providing a blade on an outer periphery of a rotating body and subsequently processing a processing schedule track of the optical element from the shallowest groove or a stepped portion. SOLUTION: In a processing order of grating grooves 6a, 6b, 6c, 6d, after processing the deepest groove 6d, is moved to a position of the shallowest groove 6a adjacent to a blade and a processing of the groove 6a is carried out. Next, a processing order is varied from a groove 6c of a second depth to the groove 6b. Accordingly, as the processing order, after the deepest groove position of a grating portion of an object to be processed is processed, the shallowest groove portion of the adjacent grating portion is processed. Next, the groove portion of the second depth of the grating portion of the object to be processed is processed. Thereafter, the processing order is subsequently varied to a shallow groove direction. An efficient processing can be carried out by a repeated processing action by teaching an order of a movement operation of X, Y, Z axis of the blade for processing a pair of grooves, a movement quantity P of the whole pairs and the number of pairs to a controlling means.