The purpose of this study was to investigate the effects of central posteroanterior mobilization on the pain, muscle tone, flexibility of trunk flexion, lumbar lordosis in patient with chronic back pain has been studied. The target subject was a 23 year old man, who had chronic back pain without surgical history within six months. The pain has been indicated by the pressure pain threshold, when the subject was pressed his spinous process of L3-L1 by the pressure of grade Ⅳ. The muscle tone, elasticity, and stiffness were measured by the MYOTONEⓇ PRO, and the flexibility of trunk flexion was evaluated by the distance from the figure tips to the floor, when subjects flexed their body. The lumbar lordosis was measured from the X-ray picture. The lumbar central posteroanterior mobilization of Maitland orthopedic physical therapy has been applied to the spinous process of L3-L1 in grade Ⅳ by five sets and 10 times for each set. According to the measurement result right after the intervention, the pain decreased from 2/10 to 1/10 based on the visual analogue scale. The flexibility of trunk flexion (distance from the finger tips to the floor) increased The muscle tone decreased from 15.3 to 14.65 and the muscle stiffness also decreased 53.5 from 310 to 256.5. However, the muscle elasticity increased from 0.89 to 1.04 and there was no changed on the lumbar lordosis as 25°. The results of the present study suggest that the central posteroanterior mobilization decrease the pain, muscle tone, and muscle stiffness of the lumbar area, however increase the muscle elasticity and flexibility of the trunk flexion.