The present invention provides an exercise method for strengthening the quadriceps and gluteal muscles while protecting knee and ankle joints, and an exercise device thereof. During exercise, the load on the opposite leg is reduced by a user taking a sitting, lying, or prone position. In addition, the lower end of an arm portion is placed on the thigh rather than the ankle or the sole of the foot to move the leg, so that the load transferred to the knee and ankle joint is minimized. And, by expanding the range of motion and the direction of movement of the hip joint, the effect of strengthening the quadriceps and gluteal muscles is increased. COPYRIGHT KIPO 2021