A thin flat cathode-ray tube can optimize stress which is generated in each part also when its screen size is increased and maintains high reliability particularly in connection strength in a joint portion between a front glass vessel and a back metal vessel, without deteriorating the joint portion in reliability also in working for mounting electric signal input terminals and an exhaust pipe on the back metal vessel. In the flat cathode-ray tube which is formed by joining side surface portions of the front glass vessel and the back metal vessel with each other, the back metal vessel has the side surface portion of a prescribed width extending along that of the front glass vessel and a bottom surface portion opposed to a fluorescent screen of the front glass vessel, while the bottom surface portion is depressed by a prescribed amount toward the fluorescent portion and a corner portion connecting the side surface portion with the bottom surface portion is at a prescribed radius of curvature.
