To provide a temperature control system capable of quickly changing the set temperature of a work to be temperature-controlled.

In this system 3 for controlling the temperature of a temperature control plate 2 provided with a plate 2A for placing a work W to be temperature-controlled and a heat exchanger 2C, a cold reserve circuit 10S and a heat reserve circuit 20S constitute respective closed loop circuits through respective circulation circuits 10, 20 connecting the fluid outlet and inlet 2Co, 2Ci of a heat exchange through storage tanks 11, 21, compression pumps 21, 22 and cooling and heating means 13, 23 and respective cold reserve and heat reserve switching valves 14, 24, and a supply side switching valve 30 for connecting the fluid outlet 2Co to one of both the circulation circuits 10, 20, a discharge side control valve 40 for leading heat exchanging fluid supplied from both the circulation circuits 10, 20 to the fluid inlet 2Ci at a prescribed flow rate ratio and a control means 50 for controlling the operation of respective valves 30, 40. 14, 24 are provided.