An ink supply device supplying ink to an ink-jet head discharging ink drops in a printer performing printing in an ink jet system, comprising: an ink tank storing ink; a deaeration portion deaerating gas dissolved in ink in an ink flow path from the ink tank to the ink jet head; an upstream-side ink flow path which is an ink flow path on the upstream side of the deaeration portion, sending ink supplied from the ink tank to the deaeration portion; and a downstream-side ink flow path which is an ink flow path on the downstream side of the deaeration portion, sending ink after passing through the deaeration portion to the ink-jet head, wherein the deaeration portion includes an ink branching portion splitting ink supplied from the upstream-side ink flow path between plural branch flow paths, plural deaeration modules (212a, 212b) which are modules for deaerating gas dissolved in ink, in which one or more modules are arranged in respective plural branch flow paths, thereby being arranged in parallel in the ink flow path, characterized in that the ink supply device further comprises: plural pumps (214a, 214b) arranged so as to correspond to the plural deaeration modules, and an ink converging portion converging the plural branch flow paths to send ink to the downstream-side ink flow path, wherein each of the plural deaeration modules is arranged between the ink branching portion and the ink converging portion in a corresponding branch flow path, and each of the plural pumps is arranged in series to a corresponding deaeration module in each of the branch flow paths, allowing ink to flow into the corresponding deaeration module. an ink tank storing ink; a deaeration portion deaerating gas dissolved in ink in an ink flow path from the ink tank to the ink jet head; an upstream-side ink flow path which is an ink flow path on the upstream side of the deaeration portion, sending ink supplied from the ink tank to the deaeration portion; and a downstream-side ink flow path which is an ink flow path on the downstream side of the deaeration portion, sending ink after passing through the deaeration portion to the ink-jet head, wherein the deaeration portion includes an ink branching portion splitting ink supplied from the upstream-side ink flow path between plural branch flow paths, plural deaeration modules (212a, 212b) which are modules for deaerating gas dissolved in ink, in which one or more modules are arranged in respective plural branch flow paths, thereby being arranged in parallel in the ink flow path, characterized in that the ink supply device further comprises: plural pumps (214a, 214b) arranged so as to correspond to the plural deaeration modules, and an ink converging portion converging the plural branch flow paths to send ink to the downstream-side ink flow path, wherein each of the plural deaeration modules is arranged between the ink branching portion and the ink converging portion in a corresponding branch flow path, and each of the plural pumps is arranged in series to a corresponding deaeration module in each of the branch flow paths, allowing ink to flow into the corresponding deaeration module. plural pumps (214a, 214b) arranged so as to correspond to the plural deaeration modules, and an ink converging portion converging the plural branch flow paths to send ink to the downstream-side ink flow path, wherein each of the plural deaeration modules is arranged between the ink branching portion and the ink converging portion in a corresponding branch flow path, and each of the plural pumps is arranged in series to a corresponding deaeration module in each of the branch flow paths, allowing ink to flow into the corresponding deaeration module.