Abstract: A manufacturing method of oxide cathode for electron tube in which adding method of scandium Sc and yttrium Y for extending duration of ternary carbonate solid solution is improved and excellent effects is obtained so that duration and electron emitting characteristics are improved. The invention is carried out by obtaining quinary (Ba, Sr, Ca, Sc, Y) carbonate and painting this on cap whereby manufacturing electron emitting substance layer. According to the invention, extension of duration and improvement of electron emitting characteristic can be obtained.