A printer comprising: a loading room into which any one of a first instant film pack or a second instant film pack is loaded, the first instant film pack including at least a plurality of first instant films and a first case which accommodates the first instant films in a stacking manner and in which a discharge port for discharging the first instant film is formed, the second instant film pack including at least a plurality of second instant films of which a dimension in a width direction is smaller than a dimension of the first instant film and a second case which accommodates the second instant films in a stacking manner and in which a discharge port for discharging the second instant film is formed; an exposure head configured to expose an image on the first instant film or the second instant film; a position alignment unit configured to align the second instant film pack so as to be shifted to one side of the loading room in the width direction; a detector that is provided on a side surface on the other side of the loading room and is configured to detect that the first instant film pack is loaded; and a processor, wherein the processor is configured to perform control to switch between exposure ranges in which the exposure head exposes the image according to a signal from the detector, wherein the dimension of the first instant film pack in the width direction is larger than the dimension of the second instant film pack, the second instant film pack has a stepped portion (25f, 25g) having a dimension larger than the dimension of the first instant film pack in a thickness direction parallel to a loading direction into the loading room and orthogonal to the width direction, and the position alignment unit includes a first position alignment unit (61a to 61c, 62a) configured to align the first instant film pack by touching both side surfaces of the first instant film pack, and a second position alignment unit (65a, 65b) configured to align the second instant film pack by being fitted to the stepped portion (25f, 25g). a loading room into which any one of a first instant film pack or a second instant film pack is loaded, the first instant film pack including at least a plurality of first instant films and a first case which accommodates the first instant films in a stacking manner and in which a discharge port for discharging the first instant film is formed, the second instant film pack including at least a plurality of second instant films of which a dimension in a width direction is smaller than a dimension of the first instant film and a second case which accommodates the second instant films in a stacking manner and in which a discharge port for discharging the second instant film is formed; an exposure head configured to expose an image on the first instant film or the second instant film; a position alignment unit configured to align the second instant film pack so as to be shifted to one side of the loading room in the width direction; a detector that is provided on a side surface on the other side of the loading room and is configured to detect that the first instant film pack is loaded; and a processor, wherein the processor is configured to perform control to switch between exposure ranges in which the exposure head exposes the image according to a signal from the detector, wherein the dimension of the first instant film pack in the width direction is larger than the dimension of the second instant film pack, the second instant film pack has a stepped portion (25f, 25g) having a dimension larger than the dimension of the first instant film pack in a thickness direction parallel to a loading direction into the loading room and orthogonal to the width direction, and the position alignment unit includes a first position alignment unit (61a to 61c, 62a) configured to align the first instant film pack by touching both side surfaces of the first instant film pack, and a second position alignment unit (65a, 65b) configured to align the second instant film pack by being fitted to the stepped portion (25f, 25g).