The purpose of this study is a practical application of the cavitation aided abrasive machining (CAAM). This study shows the machining effect of the precision abrasive machining on injection molds using the cavitation in a suction flow of slurry, which can easily finish to a fine surface by a simple apparatus. The cavitation occurred above the workpiece surface downstream of the restrictor tip because of the rapid decompression and then the abrasive grains in the water interfere with the workpiece surface by the cavitation impact. In this report, the possibility of application of the cavitation aided abrasive machining to the precision manufacturing of micro air vents on the rib of injection molds are generated by using masks of a certain thickness that are made on a special masking equipment, and the machining characteristics of micro air vents are investigated by analyzing the depth of micro grooves and the surface finish in machining of injection molds. When the depth of the micro grooves is approximately 1μm in the machining of 30 minutes, the manufacture of molding parts without burrs or residual voids is carried out by CAAM.