An injection locked odd-number frequency divider comprising: a ring oscillator that cascade-connects amplifier circuits (141, 142, 143) each including an N-channel metal oxide semiconductor transistor (111, 121, 131) and a P-channel metal oxide semiconductor transistor (112, 122, 132) in (2n + 1) (n is any natural number) stages in a ring; an electric current source that is connected to the ring oscillator and includes an N-channel metal oxide semiconductor transistor that drives the ring oscillator; and a differential signal injection circuit that outputs an injection signal to the ring oscillator and outputs a reverse phase signal of the injection signal as a differential signal to the electric current source, characterized in that the drain of the N-channel metal oxide semiconductor transistor of the electric current source is connected to the source of each of the N-channel metal oxide semiconductor transistors (111, 121, 131) of the ring oscillator, each N-channel metal oxide semiconductor transistor (111, 121, 131) being cascade-connected in (2n + 1) stages in the ring; the differential signal injection circuit outputs the injection signal to the gate of each of the P-channel metal oxide semiconductor transistors (112, 122, 132) of the ring oscillator, each P-channel metal oxide semiconductor transistor (112, 122, 132) being cascade-connected in (2n + 1) stages in the ring, and outputs the differential signal to the gate of the N-channel metal oxide semiconductor transistor of the electric current source; and a feedback output from an amplifier circuit in the last stage is inputted to the gate of the N-channel transistor of the amplifier circuit in the first stage among the amplifier circuits (141, 142, 143) cascade-connected in (2n + 1) stages in the ring in the ring oscillator. a ring oscillator that cascade-connects amplifier circuits (141, 142, 143) each including an N-channel metal oxide semiconductor transistor (111, 121, 131) and a P-channel metal oxide semiconductor transistor (112, 122, 132) in (2n + 1) (n is any natural number) stages in a ring; an electric current source that is connected to the ring oscillator and includes an N-channel metal oxide semiconductor transistor that drives the ring oscillator; and a differential signal injection circuit that outputs an injection signal to the ring oscillator and outputs a reverse phase signal of the injection signal as a differential signal to the electric current source, characterized in that the drain of the N-channel metal oxide semiconductor transistor of the electric current source is connected to the source of each of the N-channel metal oxide semiconductor transistors (111, 121, 131) of the ring oscillator, each N-channel metal oxide semiconductor transistor (111, 121, 131) being cascade-connected in (2n + 1) stages in the ring; the differential signal injection circuit outputs the injection signal to the gate of each of the P-channel metal oxide semiconductor transistors (112, 122, 132) of the ring oscillator, each P-channel metal oxide semiconductor transistor (112, 122, 132) being cascade-connected in (2n + 1) stages in the ring, and outputs the differential signal to the gate of the N-channel metal oxide semiconductor transistor of the electric current source; and a feedback output from an amplifier circuit in the last stage is inputted to the gate of the N-channel transistor of the amplifier circuit in the first stage among the amplifier circuits (141, 142, 143) cascade-connected in (2n + 1) stages in the ring in the ring oscillator.