According to one embodiment, an X-ray tube, including a cathode including a filament including a leg portion extending from a coil to a distal portion and including a corner portion at the distal portion, a support terminal including a gap, and including an opening portion in which the gap is opened and a bottom portion located on a side opposite to the opening portion, and a cathode cup being connected to the support terminal, the distal portion being located in the gap, the support terminal including a protruding portion protruding in the gap, being located more closely to the bottom portion side than the distal portion, and being joined to the corner portion of the leg portion.