The purpose of the present work is to obtain the most effective controlling parameters for heat treatment of needle bearing steel , the effect of controlling parameters such as Holding Time, Carburizing temperature, Carbon Potential and Quenching temperature on hardness value of bearing steel. In this case, 9 combinations of the above mentioned 4 parameters were set and Taguchi’s method was followed accordingly. Signal to noise ratio (S/N) analysis showed that effective hardness value was obtained when the parameters were chosen on the basis of “Smaller the better” category which were Holding Time: 40 min., Carbon Potential: 1.2 m3/hr., Carburizing Temperature: 8900C and Quenching Time:4 min.