A new phase-modulation device having a simple structure and high reliability was constructed using a short amorphous wire. A high frequency ac current (carrier) and a signal current are simultaneously applied through the wire having the large Barkhausen effect at the circumferential flux change. An accurately linear modulation characteristics up to 0.6 π was obtained using a triangular wave ac current applied to a tension-annealed wire of 30μm diameter and 5 mm length. The simple and reliable phase modulation device is expected to be applied to the field of factory automation communication network.