After medieval times, the supreme leaders such as chief priests of the sect and religious community which had been succeeded for generations by kechimyaku sojo (Transmission of the Heritage; the secret transmission from the Great Master to only one disciple) and the head priests of the grand head temple had been called hoshu as a honorific title.
中世以後、血脈相承によって代々受け継がれてきた宗門・教団の門主・管長などの最高指導者、大本山住職などを尊んで法主と呼ぶようになった。