asically, a current sensor is consisted of ferromagnetic core, coil and magnetic sensor. To measure alternative current, 2 methods are existed. The first method is measurement of the induced elect개motive force of coil, which is wired in ferromagnetic core. The second measurement method is utilized with the magnetic sensor, such as hall effect sensor. However, those methods have some problem. This paper introduces the development of direct current sensor using magnetostriction. Principally, magnetostriction is the phenomenon of expansion of contraction when ferromagnetic core is placed in an alternating magnetic field. This induced electromagnetic induction and the direct current can be measured such as measurement of alternating current.