The microelectronics industry in Japan has grown rapidly in recent years. In general, all steps in the semiconductor process are implemented in a clean room. The air in the clean room is maintained at a well-controlled temperature and is continuously filtered and recirculated. Also the air in the clean room is monitored and classified with respect to particulates. A “class 1000” environment has a maximum of 1000 partic1es per cubic foot with particle size larger than 0.5 μm. Five years have passed since the clean rooms of class 1000 and 10000 in the Department of Electronics, Hiroshima Institute of Technology was established in 1986. An outline and the know-how on the maintenance of the clean room is described.