The modern distribution industry demands improved efficiency in logistics to lower prices while maintaining product quality. However, the efficiency of picking (collecting commodities in a warehouse), which accounts for a large percentage of the total logistics cost, has not improved significantly. In this study, we propose a traveling route derivation method that allows the warehouse layout to be set arbitrarily. Specifically, we combined the A* and genetic algorithms to reduce the walking distance of picking workers and improve picking efficiency in a warehouse. Furthermore, we simulated the route derivation for picking based on practical work, the walking distances were compared using a comparison method (brute-force method and without A* algorithm method), and the usefulness of the proposed method was evaluated.