Abstract
§1 This paper treats a problem on Qahan (_中合罕_) in the language the Secret History of the Mongols. The literary form for this qahan generally considered as qaγan. However, can the form qaγan of literary Mongolian correspond to qahan in the language of the Secret History? is not necessarily correct. Following the transcriptional principle in the Secret History, we can expect qa'an instead of qahan for the literary form qaγan.
This is easily recognized by the following comparative table among the language of the Secret History, literary Mongolian, and modern Khalkha Mongolian.
