An ink-jet printer (100, 101, 102) provided with a circulation flow passage for circulating ink, comprising: a printing part having a plurality of printing heads, each of which has a nozzle for discharging the ink formed therein; a buffer tank for storing the ink; a heat exchanger for adjusting the temperature of the ink; a manifold for diverging the flow passage of the ink; a main flow pipe for successively connecting the buffer tank, the heat exchanger and the manifold with one another; a sub-flow pipe for connecting the manifold and the buffer tank with each other; a supply flow pipe for connecting the manifold and the printing part; a collection flow pipe for connecting the printing part and the buffer tank with each other; and wherein the main flow pipe and the sub-flow pipe constitute a first circulation flow passage for circulating the ink and the main flow pipe, the supply flow pipe and the collection flow pipe constitute a second circulation flow passage for circulating the ink, characterized in that: the ink-jet printer comprises pumps that are respectively installed on the sub-flow pipe, the supply flow pipe and the collection flow pipe so as to flow the ink, the printing part has a distribution tank for storing the ink to be distributed to the plural printing heads, the distribution tank is constituted by a first distribution tank and a second distribution tank, and the first distribution tank is configured to store the ink to be supplied to the printing heads and the second distribution tank is configured to store the ink collected from the printing heads, the collection flow pipe is constituted by a first collection flow pipe that connects the first distribution tank of the printing part and the buffer tank and a second collection flow pipe (53b2) that connects the second distribution tank of the printing part and the buffer tank, and wherein pumps for flowing the ink are respectively installed on the first collection flow pipe (53b1) and the second collection flow pipe (53b2), the first collection flow pipe (53b1) and the second collection flow pipe (53b2) are independent from each other. a printing part having a plurality of printing heads, each of which has a nozzle for discharging the ink formed therein; a buffer tank for storing the ink; a heat exchanger for adjusting the temperature of the ink; a manifold for diverging the flow passage of the ink; a main flow pipe for successively connecting the buffer tank, the heat exchanger and the manifold with one another; a sub-flow pipe for connecting the manifold and the buffer tank with each other; a supply flow pipe for connecting the manifold and the printing part; a collection flow pipe for connecting the printing part and the buffer tank with each other; and wherein the main flow pipe and the sub-flow pipe constitute a first circulation flow passage for circulating the ink and the main flow pipe, the supply flow pipe and the collection flow pipe constitute a second circulation flow passage for circulating the ink, characterized in that: the ink-jet printer comprises pumps that are respectively installed on the sub-flow pipe, the supply flow pipe and the collection flow pipe so as to flow the ink, the printing part has a distribution tank for storing the ink to be distributed to the plural printing heads, the distribution tank is constituted by a first distribution tank and a second distribution tank, and the first distribution tank is configured to store the ink to be supplied to the printing heads and the second distribution tank is configured to store the ink collected from the printing heads, the collection flow pipe is constituted by a first collection flow pipe that connects the first distribution tank of the printing part and the buffer tank and a second collection flow pipe (53b2) that connects the second distribution tank of the printing part and the buffer tank, and wherein pumps for flowing the ink are respectively installed on the first collection flow pipe (53b1) and the second collection flow pipe (53b2), the first collection flow pipe (53b1) and the second collection flow pipe (53b2) are independent from each other. the ink-jet printer comprises pumps that are respectively installed on the sub-flow pipe, the supply flow pipe and the collection flow pipe so as to flow the ink, the printing part has a distribution tank for storing the ink to be distributed to the plural printing heads, the distribution tank is constituted by a first distribution tank and a second distribution tank, and the first distribution tank is configured to store the ink to be supplied to the printing heads and the second distribution tank is configured to store the ink collected from the printing heads, the collection flow pipe is constituted by a first collection flow pipe that connects the first distribution tank of the printing part and the buffer tank and a second collection flow pipe (53b2) that connects the second distribution tank of the printing part and the buffer tank, and wherein pumps for flowing the ink are respectively installed on the first collection flow pipe (53b1) and the second collection flow pipe (53b2), the first collection flow pipe (53b1) and the second collection flow pipe (53b2) are independent from each other.