In a partial-vacuum-type, electron-beam irradiation system having a construction such that a static-pressure floating pad is connected to a vacuum chamber incorporating an electron-beam column, and an electron-beam passes through an electron-beam passage of the static-pressure floating pad to impinge on a body to be irradiated in the condition where the static-pressure floating pad is contactlessly attracted to the body to be irradiated, a vacuum-seal valve for opening and closing the electron-beam passage is provided inside the static-pressure floating pad, and when the static-pressure floating pad is separated away from the body to be irradiated, the vacuum-seal valve is actuated to close the electron-beam passage, whereby the atmospheric air is prevented from flowing into the vacuum chamber.