An X-ray image pickup device has a two-dimensional image reading device which is constituted by two-dimensionally forming a plurality of photoelectric conversion elements on an insulating substrate, and has switching elements in the vicinities of these photoelectric conversion elements, a phosphor which is formed on the two-dimensional image reading device and serves as a wavelength converter for converting X-ray radiation into visible light, and a grid plate which is formed on the phosphor and guides only X-rays from a specific direction toward the phosphor and the two-dimensional image reading device, whereby a next-generation X-ray image pickup device which can improve diagnostic efficiency that cannot be attained by the conventional film method, and has a high space factor and a high S/N ratio that cannot be attained by the CCD method can be provided.