In a sheet feeding mechanism wherein a spring can be used to properly regulate a sheet feeding position, sheets are not deformed in spite of the urging force of the spring, and a required conveying force is prevented from being increased after sheet feeding. Specifically, immediately before a sheet is fed, a driving mechanism is used to move a slide plate leftward. A driving portion of the slide plate pushes an arm of a lever to rotate the lever counterclockwise against a tension spring. Thus, a connecting portion of the lever pushes an interlocking portion of a biasing plate downward. That part of the biasing plate rotates clockwise against the force exerted as a set spring portion is urged counterclockwise. In conjunction with this rotation, a biasing portion rotates clockwise to urge printing sheets to press them against a reference surface of a case.

Provided is a removably detachable portable media cassette for a printing apparatus. The media cassette of a printing apparatus includes a loading case to load a first medium. A spacer is detachably installed on the loading case to guide two or more media having different sizes from that of the first medium.