Countermeasures against heat are one of the important issues for IC chips because the increased IC chip temperature causes malfunction. But the traditional countermeasures such as the cooling fan and the heat sink have a limitation in cooling performance. So we have focused on the cooling channel with superior cooling performance. In this paper, a design method of cooling channel by utilizing the optimality of branching system has been suggested. The cooling performances of the proposed design method have been evaluated by comparing the results of CAE simulation and an experiment.