A disc-like grinding wheel 5 is formed with a circumferential groove 5a, the opposite walls of which define grinding surfaces 5b. A rotated carrier 3 brings a load pin 55 into rotary movement relative to the grinding wheel 5 rotated about an axis 5z, so as to pass the load pin 55 through space between the grinding surfaces 5b, whereby opposite end faces 55a of the load pin 55 are ground simultaneously. Thus, time taken by a grinding process may be reduced as compared with a conventional method wherein one end face is ground at a time.