A transmission type X-ray generator comprising: an electron source for generating an electron beam having an energy of 10keV to 200keV; an anode having an electron path formation member and a target area, wherein the electron path formation member has a circular opening so as to define an electron path such that an inner wall of the electron path formation member surrounds a periphery of the electron path; and the target area comprises an insulating substrate; a conductive layer provided on the insulating substrate; and a target disposed on the conductive layer or the insulating substrate and provided at the circular opening of the electron path formation member and, such that electrons from the electron source pass through the electron path to irradiate the target so as to generate an X-ray, wherein the conductive layer is provided in at least a part of a peripheral area of the substrate which is not covered with the target, wherein: the target and the conductive layer are electrically connected to each other; the target area and the electron path formation member are soldered to each other; the substrate and the conductive layer are also soldered to the electron path formation member; the target is disposed at a central area of the insulating substrate; the inner wall surface of the electron path formation member has a sub X-ray generating portion configured such that electrons reflected from the target and irradiating the sub X-ray generating portion generate a sub X-ray; and at least a part of the target area at a peripheral area of the substrate which is not covered with the target has higher transmittance with respect to the sub X-ray than that at the central area where the substrate is covered with the target, and a material of the inner wall surface of the electron path formation member is made of a same material as the target. an electron source for generating an electron beam having an energy of 10keV to 200keV; an anode having an electron path formation member and a target area, wherein the electron path formation member has a circular opening so as to define an electron path such that an inner wall of the electron path formation member surrounds a periphery of the electron path; and the target area comprises an insulating substrate; a conductive layer provided on the insulating substrate; and a target disposed on the conductive layer or the insulating substrate and provided at the circular opening of the electron path formation member and, such that electrons from the electron source pass through the electron path to irradiate the target so as to generate an X-ray, an insulating substrate; a conductive layer provided on the insulating substrate; and a target disposed on the conductive layer or the insulating substrate and provided at the circular opening of the electron path formation member and, such that electrons from the electron source pass through the electron path to irradiate the target so as to generate an X-ray, the target and the conductive layer are electrically connected to each other; the target area and the electron path formation member are soldered to each other; the substrate and the conductive layer are also soldered to the electron path formation member; the target is disposed at a central area of the insulating substrate; the inner wall surface of the electron path formation member has a sub X-ray generating portion configured such that electrons reflected from the target and irradiating the sub X-ray generating portion generate a sub X-ray; and at least a part of the target area at a peripheral area of the substrate which is not covered with the target has higher transmittance with respect to the sub X-ray than that at the central area where the substrate is covered with the target, and a material of the inner wall surface of the electron path formation member is made of a same material as the target.