A liquid discharging-type image forming apparatus capable of securely eliminating mixed air bubbles from the ink liquid and forming a stable image. The apparatus includes: a sub tank 35 of which negative pressure amount is detected; a pump 115 sucking ink when the detected amount of the sub tank 35 is lower than a predetermined amount so that the sub tank 35 and recording heads 34 have negative pressure; a second backflow prevention unit 203 to stop the sent ink to be reserved in a second liquid container 201, which is pressurized as ink increases. When the ink is again filled in the sub tank 35, the ink is sent from the second liquid container 201 before being sent from the first liquid container. Accordingly, ink is not accumulated in the second liquid container 201, allowing the second liquid container 201 to be smaller and the image forming apparatus as a whole to be more compact.