This paper describes the comparison of octree data structure intending to find a suitable one for the simulation with a solution adaptive octree mesh. We compared three different kind of implementation of octree, such as Standard, FTT and Pedigree FTT that we proposed, performing simulation programs of a steady-state heat transfer problem. It was found that Pedigree FTT appeared to be most suitable among them from the view points of memory utilization and calculation cost.