A case body of an ink cartridge has a recording ink storage chamber containing a recording ink and a waste-ink storage chamber containing an ink coagulant. The recording ink is supplied to a recording head of an ink jet recording apparatus. A head cleaning unit collects waste-ink from the recording head and feeds it to the waste-ink storage chamber. A heater heats the waste-ink and the ink coagulant in the waste-ink storage chamber, so that the ink coagulant melts and mixes with the waste-ink. The mixture of the ink coagulant and the waste-ink is cooled and solidified into gel. The gelled mixture of the waste-ink and the ink coagulant can be easily taken out of the waste-ink storage chamber by heating to liquefy it again, facilitating recycling the case body.