According to one embodiment, an X-ray tube includes an anode target, a cathode including a filament and a convergence electrode which includes a groove portion, and an envelope. The groove portion includes a pair of first bottom surfaces which are located in the same plane as the filament and between which the filament is interposed in a width direction of the groove portion, and a pair of second bottom surfaces between which the filament and the pair of first bottom surfaces are interposed in a length direction of the groove portion and which are located closer to an opening of the groove portion than the pair of first bottom surfaces.