Cosmic-ray electron observations in the energy range from 30 GeV to 3 TeV have been performed by using balloon-borne emulsion chambers. The emulsion chamber is an excellent imaging detector with a high position resolution of 1µm. This imaging capability enables the emulsion chamber to identify electrons against gamma rays and protons, determine electron energies, and be a thin and low mass detector. The performance of the emulsion chamber was examined by Monte Carlo simulations of Geant4 and EPICS with the results of accelerator beam tests of electrons in 50 GeV – 250 GeV at CERN-SPS. In order to evaluate the possible systematic differences, especially at energies greater than 250 GeV, we made a comparison between completely different simulation codes of Geant4 and EPICS. As the results, we confirmed that the systematic differences are 1 – 3 % for the integral track lengths, which are sufficiently-small for the energy determinations with the emulsion chambers.