It is an object of the present invention to provide a lower half body module of a bipedal walking robot which is excellent in practicality in the point that it is possible to transport a heavy load, and which is excellent in the degree of freedom in designing in the point that it is possible to mount or incorporate an upper half body having a large weight. Therefore, this is why legs of the lower half body module are constituted by a parallel link mechanism to sustain a large load. The lower half body module (1) of the present invention includes a base (2), a right foot (3) and a left foot (4), a plurality of passive joints (6, 7, 8) which are respectively provided on the base (2), the right foot (3) and the left foot (4), and parallel link mechanism portions (1a, 1b) which are respectively provided between the passive joint (6) provided on the base (2) and the passive joints (7, 8) provided on the right foot (3) and between the passive joint (6) provided on the base (2) and the passive joints (7, 8) provided on the left foot (4).