To provide a book/document holding device capable of stably holding even a think and heavy book in arbitrary attitude though it is impossible by a conventional device, and being used as a document loading space in inputting to a personal computer.

A front plate 2 made of a transparent member is located oppositely to a back plate 5 mounted on a supporting arm 3, and is demountably mounted on the back plate 5, and a book/document is inserted between the front plate 2 and the back plate 5, so that the book/document is read through the front plate 2. A supporting position changing means 4 is mounted on the back face 18 side of the back plate 5 for changing a back plate supporting position of the supporting arm 3. The front plate 2 is demountably mounted to the back plate 5 through a clearance adjusting means 6 capable of adjusting a clearance between the front plate 2 and the back plate 5. A drop of book/ document prevention wall 36D is formed on a lower edge of at least one of the front plate 2 and the back plate 5.