Provided is an X-ray generator (10) which causes electrons having passed through an electron path (4), formed by an electron path formation member (3) surrounding the periphery of the electron path (4), to be emitted against a target to generate an X-ray, in which: an X-ray generated when the sub X-ray generating portion (5) provided in the electron path (4) is irradiated with the electrons backscatterred off the target is capable of being taken out; a material which constitutes the target and a material which constitutes at least the sub X-ray generating portion (5) of the electron path formation member (3) are the same material of which atomic number is 40 or greater. X-ray generation efficiency can be improved by effectively using the electrons backscatterred off the transmission target.