Recently, many people are interested in the ride quality of vehicles. Human vibration model is helpful to investigate ride quality. Therefore, the objective of this study is to develop a human vibration model in a sitting posture. The developed model consists of sis rigid bodies, three joints and twenty-six Hill-type muscle models. The model is in a sitting posture and connected with chair by spring-damper. Posture of the model is controlled by PD controller when vertical vibration is applied on the chair. Gain values and spring-damper coefficients are obtained using a global optimization method so that vibration responses match experimental results. Apparent mass and acceleration transmissibilities relative to excitation frequency obtained from the proposed model are good agreement with those of experimental results. In addition, energy consumption of lumbar muscles relative to excitation frequency is validated qualitatively by comparing lumbar muscle oxygenation.