To select a heat sink suitable to its installing environment and to secure optimum radiation effect by installing a heat sink having a desired shape according to its installing environment.

A base station device 1 is installed outdoors and accordingly required to normally function even in a hot summer in Japan and also to be vertically or horizontally placed according to its installed situation. In this respect, the heat sinks of various designs having effective functions for radiation are prepared in order to secure a normal operation of the device 1 even in any weather environment and any environment. Then a heat sink 2 suitable to the environment of the device 1 is selected and mounted on the device 1. As a result, the optimum radiation effect is secured.