The emulsion lubrication is expected to get the effects of cooling and lubrication in metal cutting. The purpose of this research was to investigate the lubrication characteristics of the emulsion in a region of the elastohydrodynamic lubrication by experiments using o/w type emulsion lubrication. With the line contact frictional experiment apparatus which is the model of a rolling mechanism, friction coefficient, and oil film thickness were measured. By analyzing these experimental data with the variables of emulsion concentration, load, and rolling velocity, the following results are obtained. Emulsion viscosity $eta$ for the concentration and pressure can be calculated by the following equation $eta=eta_o e^{alphap}cdot e^{eta phi}$. Where $eta = (-3.7242+phi)/phi, 5%leq phi leq 15%$