A medium transferring mechanism that includes a medium inserting portion into which a sheet medium is inserted, the medium inserting portion defined by a bottom face and by a first side face and a second side face which extend from the bottom face and are opposed to each other; wherein a first guide face extending toward the first side face is formed at a forward end portion of the second side face; a second guide face extending from the second side face so as to gradually get close to a medium transferring path towards a medium transferring direction is formed above the first guide face; and a third guide face inclined downward from a lower edge of the second guide face toward an upper edge of the first guide face, is formed between the first guide face and the second guide face.