Provided is a method of designing a device, comprising the steps of determining a disposing process for each component of the device, the disposing process being selectable from a melting process, a shredding process and a renovating process, and designing a connecting part for joining two of the components of the device that would be determined to be disposed by different disposing processes in the determining step so as to be easily separated from each other. Thereby, the amount of work for dismantling the device and separating the components can be substantially reduced, and the component parts can be disposed simultaneously in most part.