This paper presents a new method of generating walking motion for bipedal robots through modular relative Jacobian, that is normally used for dual-arms. In this paper, the two legs are equivalent to the two arms of the dual-arm, while the two feet are equivalent to the two end-effectors of the dualarm. Two legs, each with three degrees-of-freedom (3-DOFs), are combined to form a 6-DOFs bipedal robot. Then the 3-DOFs relative position between the two feet of the bipedal robot are controlled as the relative end-effectors of the relative Jacobian, while the remaining 3-DOFs are used to control the robot posture. As in a robot manipulator control, the first priority is the relative feet motion, while the second priority is bipedal robot posture in the null space. It is noted that if individual leg control for each foot was used, with 3-DOFs control on each foot, there will be no more DOFs to control the biped robot posture. The control uses dynamics information on inertia, gravitational torques, and dynamically consistent relative Jacobian inverse. Bipedal walking simulation is shown in Gazebo.