A simulation apparatus includes: a view factor calculation means for calculating a view factor related to each two elements in a virtual three-dimensional space that is defined by a plurality of surface elements and a plurality of volume elements, the view factor calculation means calculating, as a view factor related to two element including one or two elements, a view factor decreased by a value corresponding to a quantity of radiation heat passing through the one or two volume elements; and a radiation heat quantity calculation means for calculating a radiation heat quantity exchanged between each two elements using each view factor calculated by the view factor calculation means, and the three-dimensional space of the simulation device is defined so that a plurality of trees in the three-dimensional space are treated as the plurality of volume elements.