A getter device capable of being re-activated as required and arranged in a narrow space in an envelope. The getter is arranged in a layer-like manner in an envelope of an electronic element to provide, in the envelope, a film-like getter for keeping an interior of the envelope at a vacuum. Electrons emitted from an electron feed section are impinged on the getter to activate it. The getter activated adsorbs thereon gas in an envelope of an image display device.