When ink is filled into an ink pack 13 including a bag part 20 and an outlet part 21, firstly, air in the bag 20 and outlet part 21 is sucked by a suction pump P2 provided for an ink pouring apparatus 30. Further, by a first measuring pipe 43, ink supplied from a main tank 31 is poured through the outlet part 21 into the bag part 20. Further, by a second measuring pipe 52, the ink poured into the bag part 20 of the ink pack 13 is sucked and exhausted. Furthermore, the ink in the second measuring pipe 52 is mixed into a mixing tank 34 with ink previously supplied to the mixing tank 34 from the main tank 31. Next, the ink is supplied from the mixing tank 34 to a third measuring pipe 59, and filled from the third measuring pipe 59 through the outlet part 21 into the bag part 20.