In order to reveal the shifting mechanisms for CVT using a metal V-belt, mean coefficients of friction and shifting rate; dR/ds were introduced. Belt motion in the pulley grove was characterized using the mean coefficients of friction as parameters which identify the slippage condition of the belt in the pulley grooves. The experimental results showed that thrust force and sliding speed influenced the mean coefficients of friction. It was also revealed that the shifting rate was not influenced by transmitting torque.