A temperature control system includes a first temperature adjustment unit storing fluid at a first temperature; a second temperature adjustment unit storing fluid at a second temperature higher than the first temperature; a low-temperature flow path for passing fluid supplied from the first temperature adjustment unit; a high-temperature flow path for passing fluid supplied from the second temperature adjustment unit; a bypass flow path for circulating fluid; a combination flow path for passing fluid from the low-temperature flow path, the high-temperature flow path, and the bypass flow path merged at a merging part; a temperature adjustment part that passes fluid from the combination flow path and cools/heats a member of a semiconductor manufacturing device; and a control device that controls valve positions of variable valves attached to the three flow paths upstream of the merging part and adjusts the flow rate distribution ratio for the three flow paths.