The service life of smoke-dried wood and surface-charred wood was estimated by field stake tests. The stakes used in the trials were made from Japanese cedar (Cryptomeria japonica D. Don). The test site for smoke-dried was located in Tsukuba, Ibaraki and that for charred wood was in Takao, Tokyo, Japan. The service life of smoke-dried and surface-charred wood was estimated to around 2 years. The durability of smoke-dried and surface-charred wood in an outdoor condition was almost the same as that of the untreated sapwood.