A paper feeder includes a guide surface arranged on a paper feed cassette and a roller arranged on a cassette storage unit. When the paper feed cassette is moved along a storing direction thereof inside the cassette storage unit, the guide surface placed on the roller is slidably moved by rotation of the roller. In the paper feeder, since the cassette storage portion includes a placement surface on which the guide surface is placed by surface contact at a storage position where the paper feed cassette is stored in the cassette storage unit, the stored paper feed cassette can be maintained in a stable condition, and oscillation of the paper feed cassette generated when the papers are transported can be reduced.