We investigated the carrier concentration and Hall mobility of epitaxial beta-FeSi2 films grown on semi-insulating 4H-SiC(001) single crystals to clarify the contribution of the microstructures to their electrical conduction properties. These electrical conduction properties of epitaxial beta-FeSi2 films were changed by their grain size. The Hall mobility of the films consisting of the grains of 250-350 nm in size was limited by the grain boundaries, while it was not limited by grain boundaries for the films consisting of the coarse grains of 20-40 mu m in size but limited by defects inside the grains.