**6. Acknowledgements**

The author wish to thank Dr.Yamamoto, Directer of the Research Center of Chiyoda Technol Corp. for his fruitful discussion and Dr.Kobayashi of Nagase Landauer Co. Ltd, Dr. Kakimoto of Ishikawa Prefecture Institute of Public health and Environment Science for their excellent assistance.

The work on the environmental natural background radiation monitoring using solid state passive dosimeters was partially supported by the foundation for Open-Research Center Program from the Ministry of Education, Culture, Sport, Science and Technology of Japan and Chiyoda Technol Corp.
