To provide a radiation tube suppressing undesired discharge in an internal space and materializing a high breakdown voltage by an internal surface potential control structure of a tubular side wall that is capable of suppressing unnecessary electron emission, and provide a radiation generating apparatus using the same.

In the radiation tube, an insulating tubular side wall 4 is disposed between a cathode 2 connected to an electron gun structure 5 and an anode 3 provided with a target 12 so as to surround the electron gun structure 5. In the tubular side wall 4, a potential regulating member 13 electrically connected to potential regulating means, and regulated to a potential larger than that of the cathode 2 and smaller than that of the anode 3 is provided in the intermediate part of the tubular side wall 4 in the center axis direction thereof, the boundary portion of the potential regulating part 13 and the tubular side wall 4 cannot be directly viewed from a portion exposed to the inside of the radiation tube of the anode 3, and the potential regulating member 13 has no corner part directly viewed from the portion exposed to the inside of the radiation tube of the anode 3.