In an X-ray radiation source, a lid part is fastened to a main part with screws, so that an X-ray tube is secured to a housing while being pressed against an inner surface of the wall part a by a first circuit board. The X-ray tube can be secured stably within the housing by thus being held between the first circuit board and the wall part. The X-ray radiation source uses the first circuit board incorporated in the housing itself for pressing the X-ray tube. This makes it unnecessary to provide new members for pressing the X-ray tube and can prevent the device structure from becoming complicated.