A printer includes a chassis, an ink cartridge, and an adjusting unit. The ink cartridge carrier is mounted to the chassis. A projection extends from the ink cartridge carrier. The adjusting unit includes a rotating shaft, a cam fixed to the rotating shaft, and a gear fixed to the rotating shaft. The gear includes a number of teeth. The rotating shaft is rotatably mounted to the ink cartridge carrier. The projection is clipped between two adjacent teeth. The cam abuts against the chassis.