This paper concerns a magnetic sensor using a vicalloy wire with uniaxial anisotropy and torsion stress. In the magnetic sensor using a compound magnetic wire, the relationship between wire length, magnetization state and the output voltage based on the large Barkhausen jump was investigated. When the specimen wire was short, magnetizations of soft and hard layers were stable only when in anti-parallel due to the demagnetizing field. This result indicated that a large output voltage might be obtained when the ratio of length to diameter of the wire was more than 100. Consequently, a pulse voltage V/sub p/ as high as 2 mV/turn was obtained in the wire even with diameter as fine as 0.1 mm and length as small as 10 mm.