Although a mechanism in which a single actuator and a wire passing through pulleys drive the joints is a strong candidate for realizing the dynamic behavior because of its appropriate weight and simple mechanism, the problem arises that the position of the pulley influences the dynamic behavior. This paper is focused on vertical jumping. In our research, we searched an appropriate set of positions of a pulley considering the practical development of the robot and derived the relationship between the position of the pulley and the force on the tips of the robot’s foot for jumping. Simulation results suggest the possibility that some sets of positions allow an error in the attachment of the pulley, and the derived relationship indicates that the ratio of the pulling force of wire and vertical force on the ground strongly constrain the position of the pulley.