Mirror surface processing by surface grinding of plastic mold STAVAX has conventionally been three processes of rough (# 325), semi-finishing (# 1200), and finishing (# 2000). We achieved to pass semi-finishing process by using "Teramate Premium" that can increase the depth of cut every pass, and got equivalent quality (surface roughness; 0.8nmRa) by two processes of roughing (# 200) and finishing (# 2000). As a result, the processing time was reduced by 33%.