In this article "Bukki-sho" (a book on mourning) is a commentary or the collections of practical cases of the Bukki-ryô (_??__??__??_ the regulation of mourning). Bukki-ryô is a law that regulates how long a man must go into mourning when his relative such as his parent, grandparent, or first cousin dies. The Tokugawa Shogunate, that enacted the Bukki-ryô and put it in force, ordered that the questions on Bukki-ryô should be addressed to the Bukki-gakaris (_??__??__??_ the officials in charge of mouning) in Ometsuke (_??__??__??_Great Inspectors) and Metsuke (_??__??_ Inspectors) of the Shogunate. After that, many private compilations which collected those questions and answers were edited, and thus we can now find a lot of Bukki-shos.<BR>These Bukki-shos were one of the most important sources of law in the Edo era ; nevertheless, they have only remained the materials for the study of family law and they have not been regarded as an independent subject of study. The chief points of this essay are how the Bukki-shos in the Edo era were compiled, how many classes and genealogies they were assorted into, how they were circulated, and how questions and answers on the Bukki-ryô, which were the core of the Bukki-shos, were asked and given.<BR>Most of the existing Bukki-shos are manuscpripts and derivatives of the "Bukki-ryô senchû" _??__??__??__??__??_ or the "Bukki-ryô-shôkai" _??__??__??__??__??_ Accordingly we can regard these two genealogies as two main currents of the Bukki-shos. While the Bukki-ryô-shô-kai was compiled by Kagemichi Toyama _??__??__??__??_, the Bukki-gakari Metsuke (_??__??__??__??__??_ Inspector in charge of mourning), who was in a position to answer the questions on the mourning, edited for the convenience of performance of his official duty, the Bukki-ry ô-senchû was compiled by Shoemon Nagayama _??__??__??__??__??__??_, the Rusui (_??__??__??_ Deputy during Absence) of the Yamagata clan _??__??__??_, who was in a position to ask questions on the mourning on behalf of his clan, in 1781. And this was the oldest of the real Bukki-shos that were not only the collection of questions and answers but also commentaries. It came to circulate through a lot of clans, and many derivatives of it were made up. Sesaemon Katô, the Rusui of the Oshi clan _??__??_, edited the "Bukki-ryô-senchûbunshaku" _??__??__??__??__??__??__??_, in which he revised and enlarged the Bukki-ryô-senchû completely, in cooperation with Dan-emon Yagi _??__??__??__??__??__??_, the Rusui of the Takasaki clan _??__??__??_, and the book also became popular.<BR>It may be said to be a most interesting fact that the real Bukki-sho was made by the clan earlier than by the Shogunate and was developed. And the fact that the Rusuis of clans made, improved and circulated these Bukki-syos show that Rusuis played an important role in making the law of the Shogunate permeate in clans.