Recently, creep feed grinding has become of major interest due to its high productivity. Effective application of grinding fluid is, however, more difficult than in the case of conventional grinding because of its long contact length between wheel and workpiece, so that thermal damage of the ground surface becomes a problem. The purpose of this study is to improve the application of grinding fluid. For that purpose it is necessary to clarify the state of grinding fluid in the arc of contact between wheel and workpiece. In this paper some workpiece models of creep feed grinding were made. Using these models velocity of the air flow along the ground groove near the point where the wheel begins to contact with the workpiece is measured. Furthermore, effect of various factors on the state of grinding fluid in the arc of contact are experimentally investigated introducing the equivalent thickness of grinding fluid.