An electrode (1) for cold cathode tube of the present invention includes a cylindrical sidewall portion (2), a bottom portion (3) provided at one end of the cylindrical sidewall portion, and an opening portion (4) provided at the other end of the cylindrical sidewall portion. The electrode is formed of a sintered body of a high melting point metal (W, Nb, Ta, Mo or Re). When an overall length of the electrode is L, an inside diameter of the cylindrical sidewall portion at a position of L/2 is d1, an inside diameter of the bottom portion is d2, and an arc of an inner surface (5) of the cylindrical sidewall portion connecting a portion of the inside diameter d1 and a portion of the inside diameter d2 is R, the electrode satisfies the following condition; L≧6 [mm], d2>d1, R≧20 [mm].