A temperature control device includes an estimator that estimates the outlet temperature of fluid at an outlet of heating tanks to which no outlet temperature sensor is provided. The temperature control device includes a control unit. For a heating tank to which an outlet temperature sensor is provided, the control unit determines a manipulated variable on the basis of the outlet temperature which has been measured and an individual target temperature. For a heating tank to which no outlet temperature sensor is provided, the control unit determines a manipulated variable on the basis of the estimated temperature estimated by the estimator and an individual target temperature. The control unit controls the outlet temperature of the heating tanks on the basis of the manipulated variables.