A controlling device comprises: a temperature ramp-up time estimating portion for estimating a required temperature ramp-up time for the controlled quantity in each individual control loop to reach a set point when the operating quantity output upper limit value of each individual control loop has been sent to a specified output upper limit value; a required output estimating portion for estimating, for each individual control loop, a required operating quantity output for the controlled quantity to reach the set point within the temperature ramp-up time; an output upper limit value setting portion for setting, temporarily, the operating quantity output as the operating quantity output upper limit value of the individual control loop; and a controlling portion that is provided for each individual control loop.