This paper describes a method of multiple cranes assignment to operators who call cranes in a factory. Due to a crane moving on a rail, there is a restriction on the movement. Therefore, the crane cannot be delivered without proper assignment. To solve the cranes assignment problem, we propose two methods. The first is the optimal solution search method which finds the minimum travel distance combination from the number of cases that are derived by calculating the distance between all the cranes and all the operators. The second is the dynamic mapping method which finds the number of operators between each crane. Simulation results show that the dynamic mapping method sometimes performs the same assignment results as the optimal solution search method, but on average, the result of dynamic mapping method is farther than the optimal solution as the number of cranes increases. When partial regions are created by using the dynamic mapping method and an optimal solution search method is applied to each region, optimal solutions can be acquired while reducing the number of calculations.