Morphological study of the muscles of the lower extremity is necessary for the analysis of the muscular function and its relation with locomotion. In this study, the muscle weight of the lower extremities from 11 adult Japanese cadavers (6 males and 5 females, aged from 50 to 91 years old) were measured. The morphological characteristic of the human lower extremity is discussed based on the relative muscular weight. The largest muscles were the gluteus maximus (the extensor at the hip joint), the vasti muscles (the extensor at the knee joint) and the soleus (the plantarflexor at the ankle joint). These results reveal that the muscles acting on one joint are developed in the human lower extremity and that these muscles have important roles in human locomotion.