A discharge port is formed in a bottom surface of ink tank. The ink tank is made to communicate with a waste ink tank by connecting the discharge port to the waste ink tank in a position lower than the discharge port, and a part of connection member is openable/closable by a valve. If the connection member is opened, ink is discharged from the discharge port of the ink tank to the waste ink tank. If impurities are deposited on the bottom surface of the ink tank, the impurities can be discharged with ink from the discharge port to the waste ink tank, thereby clogging in the nozzle head due to impurities can be reliably prevented.