This invention aims to provide a through terminal capable of maintaining air-tightness stably and an X-ray tube having the through terminal. The through terminal comprises a tubular member, a plate member formed of an insulating ceramic material and bonded to an inner periphery of the tubular member in a hermetically sealed state, and pins extending through the plate member so that the portions thereof fitted through the plate member are located inside metallic tubes respectively and bonded to the plate member in a hermetically sealed state through the tubes. The tubular member is provided on an inner periphery thereof with a stepped portion for abutment thereagainst of a plate face of the plate member. The tubular member is formed of an alloy comprising at least iron, nickel, and cobalt.