Bale is an operation of collecting livestock feed materials from field crop residue, and mechanization demand on the operation has been increased. Bailers imported from foreign countries such as Japan and European countries have been used, but those models showed improper performance in Korean situations. In recent years, a steel-roller type round baler attachable to medium size tractors(40 to 60 HP) for effective bale operation in Korea was developed. This study was conducted to evaluate field performance of the baler. For proper baling operation, engine speed was greater than 1,800rpm, average traction force and PTO torque were about 4kN and in a range of 380-671Nm, and maximum values were about 7kN and 3,000Nm, respectively. Performance evaluation tests for sudan grass, rice straw, and blue barley showed that field capacity was 0.59ha/h for blue barley and 0.99ha/h for sudan grass and rice straw. Bale weight, diameter, width, and bulk density were in ranges of 176.1~418.4kg, 1.07~1.12m, 1.02~1.04m, and 175.3~454.1kg/$m^3$. Noise sound level during the baling operation was 4dB greater than idle operation condition, which was considered to be ignorant.