Printer

A printer comprising a printing mechanism which prints on printing media with ink, and an ink container which supplies ink to the printing mechanism and comprises a cylinder having a side wall formed of transparent or semitransparent material and provided with an ink discharge port in a front end face thereof, a piston received in the cylinder to be slidable along the side wall of the cylinder in the longitudinal direction thereof, and ink between the piston and the front end face in the cylinder, wherein the improvement comprises

• a light projecting means which projects light onto the side wall of the cylinder in a predetermined position in the longitudinal direction of the cylinder,
• a photodetector which is positioned near a rear end face of the cylinder to be adapted to receive the light projected by the light projecting means and passing through the side wall of the cylinder only once, and outputs an electric signal upon receipt of light, and
• an ink remainder detecting means which detects the remainder of ink in the ink container on the basis of the electric signal output from the photodetector.