This is a book of two volumes, containing letters written by King Sejo and the replies by Hyegakjonja, Sinmi (a reverend monk, Royal Mentor). Upon hearing that Sinmi was rebuilding Sangwonsa Temple in Odaesan Mountain, wishing for the King's long life, King Sejo sent letters together with gifts of rice, cotton, hemp cloth and steel, and Sinmi wrote back to the King after receiving the royal gifts. One of the two volumes, written in pure Chinese characters, features different sugyeols (a form of signature used in Joseon Dynasty before chops were widely accepted in late 19th century) of Sinmi such as 'Sinmi', 'Hagyeol' and 'Hakjo' along with sugyeols and official seals of King Sejo and the crown prince. The other volume has the gwonseonmun (encouraging letter) both in Chinese characters and a translated version in Hangeul, with sugyeol and an official seal at the end. This book is an invaluable material for studies in Old Korean, offering a glimpse of the relationship between royal household and Buddhist scholars.