In this paper we present motion planning for tasks that require whole body motion of a humanoid robot. We address two such typical tasks, stepping over obstacles and manipulating an object, with the help of resolved momentum control (RMC) to guarantee the robot stability. For the first task, we plan the trajectories of the feet and the waist according to obstacle size. The motion of upper body is determined using RMC to keep balance. This novel planning method is adaptive to obstacle sizes and hence oriented to autonomous stepping-over of humanoid robots guided by vision. The second task is pivoting manipulation of a large object, which is suitable for precise and stable transportation of large objects. To perform this manipulation, first the object is moved by two arms using force and position control together with body balancing control while robot stays in the same place. Next the movement of the humanoid robot itself is performed by stepping using RMC. The effectiveness of proposed motion planning methods is verified by experiments and simulations.