A radiation generating apparatus 30 according to the present invention including: a radiation generating tube 10 having a target 14, a tubular shielding member 18 that shields a part of a radiation generated from the target 14 and also has an aperture 21 through which the radiation generated from the target 14 passes, and an envelope 1 that has the target 14 so as to be brought into contact with the internal space thereof and also has the tubular shielding member 18 so as to protrude toward an external space thereof; a storage container 1 for storing the radiation generating tube 3 therein; and an insulating liquid 8 that comes in contact with the tubular shielding member 18 and the storage container 1, wherein the tubular shielding member 18 has a protruding portion P, and the protruding portion P is covered with a solid insulating member 9.