This paper deals with a new truing technique for grinding wheels in which cutting edges on the grinding wheel are machined and lapped in a newly designed ultra-precision grinding machine. The newly developed grinding machine has a measuring device for cutting edge height and rotating spindles for a grinding wheel and a workpiece. Each spindle stiffness is 1 kN/μm. After applying the newly developed truing process to a #1500 diamond grinding wheel on the grinding machine, the number of accumulative cutting edges below 0.5 μm depth from the outmost wheel surface were increased by more than 32 times compared to conventional truing process. In-feed grinding achieved a surface roughness of 7 nmR<SUB>max</SUB> in ductile mode on optical glass BK 7 by a #1500 diamond grinding wheel with cutting edges of unified height.