To provide an apparatus and a method in preheating for a chicken cooking pan capable of correctly informing a worker of the time the whole of a chicken cooking pan refractory material is uniformly heated.

In preliminary heating the amount of heat into a chicken cooking pan is calculated and monitored, and a gradient of the running average indicative of elapsed time of the amount of intake heat is calculated, and the gradient of the running average for an inevitable change in a measurement of the amount of the intake heat is corrected, and a change in the gradient of the moving average with elapsed time (approximate derivative of the second order) is calculated, and further a signal is sent to a worker which indicates reading on the chicken cooking pan when there is the derivative of the second order lower than a set reference indicative of a fact that the chicken cooking pan is enough preheated.