In this paper, we propose a method to determine the optimal multiarticular muscle arrangement of a robot for a specific motion. Multiarticular muscles contribute to the realization of a musculoskeletal robot with dynamic motion ability similar to humans and animals. However, the ability is affected by the multiarticular muscle arrangement. In previous researches, the muscle arrangements of the robots were based on those of humans and animals. However, we suppose that a more suitable muscle arrangement than any other one of humans and animals can be found by limiting the variety of motions. Therefore, we focused on a specific motion, and furthermore, searched for the optimal multiarticular muscle arrangement for the specific motion. Specifically, we estimated the impulse properties of robots with a great variety of possible muscle arrangements. The impulse properties were calculated using dynamics simulation corresponding to the specific motion. Then, on the basis of the evaluation of the impulse properties, we found the optimal muscle arrangement from among 736,281 of possible muscle arrangements. Furthermore, we demonstrated the effectiveness of our method using simulation experiments. The results indicate that there is a more suitable muscle arrangement than any other one of humans and animals on condition that we focus on the specific motion.