It is object to provide a manufacturing method of an SOI substrate provided with a single-crystal semiconductor layer, even in the case where a substrate having a low allowable temperature limit, such as a glass substrate, is used and to manufacture a high-performance semiconductor device using such an SOI substrate. Light irradiation is performed on a semiconductor layer which is separated from a semiconductor substrate and bonded to a support substrate having an insulating surface, using light having a wavelength of 365 nm or more and 700 nm or less, and a film thickness d (nm) of the semiconductor layer which is irradiated with the light is made to satisfy d=.lamda./2n.times.m.+-..alpha. (nm), when a light wavelength is .lamda. (nm), a refractive index of the semiconductor layer is n, m is a natural number greater than or equal to 1 (m=1, 2, 3, 4, . . . ), and 0.ltoreq..alpha..ltoreq.10 is satisfied.