Abstract: Provided is a vacuum valve device which is capable of ensuring and maintaining smooth operation of a valve body, and in which an adequate space is ensured as a vacuuming gas flow path, and also provided is a vacuum die-casting device using the vacuum valve device. The vacuum valve device includes a piston rod and a rod seat. The piston rod includes: a rod; a piston formed at one end of the piston rod; and a guide part extending from the piston as far as the rod towards the other end of the piston rod. The rod seat has an insertion hole into which the piston rod is inserted from a first end of the insertion hole and through which the piston rod passes to a second end of the insertion hole. At least a portion of the insertion hole including the first end of the insertion hole forms the gas flow path.