An information book includes a booklet casing having a front cover, a back cover, and a middle panel foldably extended between the front and back covers. The front cover, middle panel, and back cover are adapted for overlappedly folding in a tri-fold manner and are adapted to be aligned edge-to-edge in a plane manner. The front cover has an inner indented side defining a receiving cavity therein such that the middle panel is fittedly received in the indented side of the front cover. The booklet casing further includes a binding element provided between the middle panel and the back cover along a folding line thereof for detachably binding at least an information sheet between the middle panel and the back cover. Therefore, information on the PDA and information 4on the information sheet are adapted to be read and used simultaneously.