Disclosed is a diffraction grating lens comprising a lens base (51) having a surface (51b) obtained by providing a diffraction grating (52) to the base shape of the lens base. The diffraction grating (52) has multiple ring zones (61A, 61b) and multiple first diffraction steps (65A) and second diffraction steps (65B) positioned between the ring zones. The lens base comprises a first material with a refractive index n1 (lambada) at working wavelength lambada, and the first diffraction steps (65A) and the second diffraction steps (65B) all have substantially the same height d, which fulfills equation 1, below, wherein m is the diffraction order. A first plane (66A) which delimits the positions of the tips (63A) of the first diffraction steps (65A) and a second plane (66B) which delimits the positions of the tips (63B) of the second diffraction steps (65B) are located at different positions on the optical axis (53).