To provide a folder used as a simple book rest for easily putting up a document or a book obliquely to make it easy to read when using a personal computer and in the unusable state of both hands.

The inner surface side of a back cover of the folder is provided with a book rest paper with a book bearer added thereto, and the book bearer of the book rest paper is provided with a hook fastener. The inner surface side on the front cover side of the folder is provided with a loop fastener. The book bearer is lifted to fix the hook fastener of the book bearer to the loop fastener on the front cover side. A mount paper thereby rises obliquely to become the book rest for the document. Alternately, the inside on the front cover side is provided with the book bearer and a book paper face receiver. The book paper face receiver is pulled up to allow the book bearer to rise to form the simple book rest where the book is placed to read.