Rigid conductor lines are currently used in wide ranges by subways and other railways. It is thought that the quality of current collection of rigid conductor lines is influenced by the unevenness of contact surface. Then, we developed a grinding machine to evenly smooth the contact surface. We also installed rigid conductor lines on the current collection testing equipment at the Railway Technical Research Institute, and examined the relation between contact surface and contact loss. Consequently, we confirmed that it was possible to reduce contact loss effectively by using the grinding machine.