A printer includes a roll paper holder to hold a roll paper, and a support holder to support the roll paper holder such that the roll paper holder is detachable and rotatable. The roll paper holder includes a rotation shaft, a first flange secured to the rotation shaft, a second flange provided on the rotation shaft, and a positioning flange provided on the rotation shaft and located at a predetermined position to the right of the first flange. The support holder includes a position determiner including an insertion hole housing a portion of the positioning flange in a state where the roll paper holder is rotatably supported and also including a restriction wall partitioning the insertion hole and restricting the positioning flange from moving in a main scanning direction.