An arrangement of cooling channels in a mold should be designed properly to improve productivity and formability for a molded product in injection molding, because temperature distribution on the mold is dependent on the arrangement and has some influence on molded defects. The purpose of this study is to develop a methodology for automatically designing arrangement of cooling channels so as to obtain the suitable temperature distribution to reduce molded defects and to realize high productivity. A cooling channel is modeled by a set of autonomous elements which is arranged as a line and has performance for extracting heat in the mold. The arrangement of cooling channels are automatically obtained by autonomous action of these elements, according to information sent from sources which are located on the mold cavity surface and evaluate temperature on its location. For estimating the temperature distribution, a steady-state heat conduction is assumed for heattransfer in the mold and calculated by numerical analysis. Several numerical experiments have been conducted for estimating the proposed method, and the effectiveness and feasibility have beeit confirmed for automatic design of cooling channels.