Image display device

An object of the invention is to provide a thin-film cathode having a base electrode, an upper electrode and an electron accelerator disposed therebetween and made of an insulator or a semiconductor, wherein a diode current rises with a lower threshold voltage that that in the background art, so that a diode current required for electron emission can be secured with a low voltage, and to obtain an image display device long in life and low in power consumption. Platinum-group metal (Group VIII), noble metal belonging to Group Ib, or a laminated film, a mixed film or an alloy film of those materials containing an alkali metal oxide, an alkaline earth metal compound or a compound of transition metal belonging to Group III to VII from the interface with an electron accelerator to the surface is used as an upper electrode.