We used electron beam irradiation on a laminate molded Co-Cr-Mo bulk alloy to reduce the surface roughness and increase hardness. The accelerating voltage and beam current were 40 kV and 0.5~5.0 mA, respectively. Irradiation time for each dot was 0.1 ms and the distance between dots (dot pitch) was either 0.2 or 0.4 mm, which corresponded to a scanning speed of 200 or 400 mm/s, respectively. The roughness value, Ra, decreased to 0.3~0.45 m for a beam current of 1 mA and a dot pitch of 0.02 mm. The coarse grains present in the base alloy were refined to sizes of less than 1m by rapid solidification. An increase in the Knoop hardness from 470 HK for the base metal to about 550 HK was achieved by this technique.