As the commercial space-travel market expands, the demand for understanding human motion in space is increasing. It is well known that a free-floating multibody can arbitrarily reorient itself by successive joint motions even without any external torque. In fact, during the early era of human spaceflight, NASA devised several representative maneuvers to study human motion in microgravity. This reorientation can be induced by the nonholonomy of its attitude dynamics, in which the final orientation of the multibody depends on the intermediate trajectory in joint-angle space. This trajectory dependency generally makes it difficult to obtain a joint-space trajectory that achieves an arbitrary attitude. In addition, the human body has more than 20 degrees of freedom, and nonlinear constraints, such as self-collision avoidance, define a complex feasible region in configuration space. This study addresses the constrained motion planning problem for the nonholonomic attitude reorientation of free-floating humans. The authors’ previous study derived an analytical trajectory correction method using rectilinear joint actuations in the joint angle space, but it was not applicable to problems with complex constraints. The improved motion planning method achieves efficient constraint handling, thereby improving the ability to obtain feasible joint-angle trajectories.