This paper describes improvement for wheel slip and re-adhesion control for electric locomotives with induction motor vector control. Compared with the conventional slip frequency method, the torque response is much improved by the vector control. By referring the re-adhesion process for the traditional rectifier controlled do-motor locomotives, suitable torque reduction to an induction motor is applied in accordance with the wheel slip speed. The test results by the series EH500 locomotive for Japan Freight Railway Company, show much improvement for the re-adhesion process especially when a steeper torque reduction ratio is applied.