PURPOSE: To easily fit a paper feed unit as an option to a recorder main unit even by a user.

CONSTITUTION: A hook 13b locked to be hooked to a bottom part engaging hole of a recorder main unit and an engaging lever 16 locked to be hooked to an engaged member of the recorder main unit are provided, and attachment to a bottom part of the recorder main unit can be performed by these hook 13b and engaging lever 16. Cassette guides 12, cassette storage space S for storing a paper feed cassette mounted to be guided by these cassette guides 12 and a paper feed means for feeding paper sheet by sheet to the recorder main unit by separating the paper in the paper feed cassette stored in this cassette storage space S are provided.