It has long been assumed that the term, "yagai kyouiku, " or "outdoor education" was first used in Eiji Ukai's 1923 book entitled Nihon arupusu to rinkan gakkou (The Japan Alps and Forest School) . However, as computerization of reference documents and database management technologies have rapidly advanced, the objectives of this study were to examine documents from the Meiji and Taisho eras, and clarify the documentation of the history of "outdoor education" in Japan by determining when the term was first used, and its meanings.<BR>The term "outdoor education" was first used in 1907 in reference to soldier training by the Japanese armed forces. The term was used when referring to training in the field, in contrast to indoor training. In addition, it was Hugh Broughton, in The Open Air School (Yagai gakkou) , translated in 1919 by the Osaka Anti-Tuberculosis Association, who used the term "outdoor education" in a way close to the current terminology. In this book, the term "outdoor education" was used in reference to forest schools and seaside schools. Thus, the term's use in reference to forest schools had been used 4 years before Ukai. However, the term "outdoor education" was not generally recognized to mean education that took place outdoors. Other terms such as "yagai kyouju" ("outdoor teaching"), "yagai kyouji" ("outdoor instruction"), and "yagai gakkou" ("outdoor school") were also used in the same way.