Kinetics of the reaction of 2-phenylethylarenesulfonates with pyridine in acetonitrile were investigated by an electric conductivity method under 1 to 2,000 bars and at 40∼60${circ}C$. The rates of these reactions were increased with raising temperatures and pressures, but less than those of the reactions of benzyl benzenesulfonate with pyridine in acetoneitrile were investigated by an electric conductivity method under 1 to 2,000 bars and at 40~60${circ}C$ .The rates of these reactions were increased with raising temperatures and pressures, but less than those of the reaction of benzyl benzenesulfonate with pyridine in acetone. The activation volumes and activation entropies of 2-phenylethyl m-nosylate were more negatively large than those of benzyl benzenesulfonate. From these phenomena it can be deduced that 2-phenylethyl system has more firmly $S_N2$ character in tranistion state. The Hammett reaction constants are also estimated from the second-order reaction constants. With increasing pressures the reaction parameters $({ ho})$ were decreased, but the $S_N2$ characters were increased. From these results, the reaction mechanism can be adequately described as typical $S_N2$ process under high pressure.