This paper describes fiber-optic current sensor using SF-4 flint glass for the first time, ails the flint glass has been theoretically analyzed by jones matrix and experimentally verified. Verdet constant of SF-4 flint glass, which determines the sensitivity of current sensor, has been experimentally found as 0.0606(min/g.cm). It is relatively lower value than currently used faraday rotators such as FR-5, SF-6 flint glasses and YIG. The fiber.optic current sensor system was established and the current measurement was performed in the range of 100-600 (A) and 100- 500 (G). It has beenfhown by the experi-mental results that the detector output linearly increased in proportion to the current. Since these experimental results were in good agreement with theoretical results, it has been shown that SF-4 flint glass can be used for the magnetooptic current sensor.