The disclosure discloses a printer including a cartridge holder, a feeder, a printing head, a first sensor, and a second sensor. The cartridge holder is configured to attach and detach a medium cartridge having a print-receiving medium. The first sensor is configured to bring a detector into contact with the medium cartridge and thereby detect first information related to the print-receiving medium, based on a result of the contact. The second sensor is configured to project light to the medium cartridge and thereby detect second information related to the print-receiving medium, based on a result of light reception corresponding to the projected light. The first sensor and the second sensor are integrated as a sensor unit configured to perform an advancing/retreating motion toward/from the medium cartridge.