A source grating for a Talbot-Lau-type interferometer includes a plurality of channels having incident apertures provided on a side irradiated with X-rays and exit apertures provided on an opposite side of the side irradiated with the X-rays; the exit apertures of the channels have an aperture area smaller than an aperture area of the incident apertures; and the exit apertures of the channels are arranged so that interference fringes of Talbot self-images formed by X-rays exiting from the exit apertures of the adjacent channels are aligned with each other.