As the mining pollution damage caused by the Ashio copper mine became serious, Shozo TANAKA, a member of the House of Representatives, set up a mining damage office for both Ibaragi and Gunma Prefecture on October 4, 1896 at Unryu-ji Temple in Watase Village, Oura County, Gunma Prefecture (the present Tatebayashi City, Gunma Prefecture.)
足尾銅山による鉱毒被害が増大すると、衆議院議員田中正造の主導の下、1896年10月4日、群馬県邑楽郡渡瀬村(群馬県)（現館林市）にある雲龍寺に、栃木・群馬両県鉱毒事務所がおかれた。