A new ternary full adder using the current controlled negative-resistance circuit is described. The full adder is constructed from the modified-half-adder which was devised by making use of a negative resistance circuit. This full adder makes the number of its gates decrease and makes its own speed increase in comparison with the full adders which had been introduced previously. It is convenient to construct to the integrated circuit because transistor, SBD(Schottky Barrier Diode) and resistors were used as the circuit elements.