A head unit (200) and a sensor unit (300) are freely Rotatably mounted in a printer main body (100). A rod-shaped portion (320) is projectingly provided to the tip portion of the sensor unit (300), and a first catching portion is provided to the rod-shaped portion (320). Furthermore, a first fixing member (220) is provided to the tip portion of the head unit (200), and the first fixing member (220) is freely detachably fitted to the first catching portion.