An ink-feeding device is provided in which the pressure applied to the ink in the printing head can be adjusted arbitrarily irrespective of the relative positions of the ink container and the printing head. Inside the sub-tank 80, a pressure-adjusting pump 82 is installed for applying a suitable pressure to many nozzles 22Kn of the printing head 22K. This pressure-adjusting pump 82 is placed a little above the bottom face of the sub-tank 80 at a prescribed distance from the bottom face. Thereby the pressure-adjusting pump 82 is immersed in the ink held in the sub-tank 80. A drive unit 83 for driving the pressure-adjusting pump 82 is placed above the sub-tank 80. On the upper wall of the sub-tank 80, an air-vent valve 84 is fixed to bring the inside pressure in the sub-tank 80 to an atmospheric pressure. The inside pressure in the sub-tank 80 is made equal to the atmospheric pressure by opening the air-vent valve 84.