The condensation heat transfer characteristic curves for a ternary vapor mixture of water, ethanol, and air (or nitrogen) under several ethanol concentrations and relatively low concentrations of air (or nitrogen) were measured. The effect of non-condensable gas oil several different domains in the condensation curves was discussed. The effect of non-condensable gas in the domains controlled by tire diffusion resistance and tire filutwise condensation was not notable; whereas that in the domain dominated by the condensate resistance of dropwise mode was remarkable. Moreover, variations due to changes in non-condensable gas concentration of several characteristic points representing tire curves were discussed.