The author describes 1. The classification and characteristics of various thick seam mining techniques in various Japanese coal mines. 2. Practices of thick seam mining methods experienced in Taiheiyo Coal Mine. Currently, thick single lift, simultaneous multi lift and non simul- taneous multi lift mining methods are adopted as underground flat thick seam excavations in Japan. These are now reliable and effective in increasing the extraction ratio. At Kushiro Colliery of Taiheiyo Coal Mining Co., these three thick seam mining methods have been used. According to the results, if solidification of the top lift goaf is essential, the non simul- taneous multi lift mining method is the most effective in increasing the extraction ratio without minimising productivity of each lift and it points out that further development of this method is necessary.