There is provided a diffractive element including a first member 2, which includes a first resin 2a and has a predetermined refractive index, and a second member 3, which has the same refractive index as the first member 2 having the predetermined refractive index in one wavelength of light and has a refractive index different from the first member 2 having the predetermined refractive index in the other wavelength of light. The first member 2 and the second member 3 are alternately arranged within an incidence plane of the two wavelengths of light, thereby constituting a diffraction grating. The second member 3 includes a second resin 3a to dissolve an organic matter 5 having optical absorption in a predetermined wavelength range at a molecular level, whereby the refractive index of the second member 3 is formed.