An X-ray generator includes: a line X-ray source; a multilayer film mirror; and a side-by-side reflecting mirror including two concave mirrors joined together so as to share a join line. A cross section of a reflecting surface of the multilayer film mirror has a parabolic shape, and a focus of the parabolic shape is located at the line X-ray source. Cross sections of reflecting surfaces of the two concave mirrors of the side-by-side reflecting mirror each have a parabolic shape, and each of focuses of the parabolic shapes is located on a side opposite to the multilayer film mirror. An extended line of the join line of the side-by-side reflecting mirror passes through the multilayer film mirror and the line X-ray source as viewed in a plan view.