To provide a book holder which can appropriately keep a book open state with a simple structure and is easy to handle.

A book holder has a back plate 1, a front plate 2, and a hinge part 3 for rotatably joining upper sides 1a, 2a of the plates 1, 2, and holds a book B open between the two plates 1 and 2. The front plate 2 is composed transparent or has light transmissivity. The back plate 1 is provided with a vertically long slot 1e where a back Bb of the open book B at a position in the middle of the horizontal direction.