To provide a heat analytic method capable of conducting an accurate analysis of analytic object system, through a simple method, without requiring much labor, and in a short time, concerning the heat analysis of heat exchanger for performing energy transmission from high temperature side fluid to low temperature side fluid.

The analytic object system is divided into plural divided blocks 10 along with a 1st flowing direction D1, in which a high temperature side fluid 1 flows, and a check object divided model provided with a high temperature side channel part 4, heat conduction boundary surface 6 and low temperature side channel part 5 is generated. Then, outlet/inlet physical quantity is made correspondent between respective divided blocks 10 along with the 1st flowing direction D1 and for each correspondent divided block 10, a heat exchange check object model composed of thermally connected plural check object divided models is constituted. These check object divided models are respectively regarded as heat exchange models, in which the high temperature side fluid 1 and a low temperature side fluid 2 flow in the 1st flowing direction D1, a convergent solution is found and heat analysis is performed.