To highly accurately measure a wavefront aberration of light waves output from an optical member with the use of a compact member without carrying out a complicate optical axis adjustment by performing an integration operation process to interference fringe data obtained with the use of a corner cube.

A laser luminous flux 16 from a light source 12 which is output from a collimator lens 10 is irradiated to a reference plate 20. The passing luminous flux is irradiated to a corner cube 24 positioned on a plate 22 nearly parallel to the reference plate 20. Interference fringe data generated by an interference between a reflecting light from the corner cube 24 and a reflecting light from the reference plate 20 is obtained every time the corner cube 24 is moved on the plate 22. Based on the interference fringe data, an angle of incidence θ of the luminous flux entering the corner cube 24 is obtained for each movement position of the corner cube 24. The obtained angle of incidence θis integrated, whereby a wavefront shape of light waves output from the collimator lens 10 is obtained.