In order to clarify the mechanisms of transition from dropwise to filmwise condensation heat transfer, dropwise condensation curves on a copper surface adsorbing a common monolayer type promoter, trilauryl trithiophosphite, were measured precisely for the substances having various physical properties, i.e. propylene glycol, ethylene glycol and glycerol vapors, at several reduced pressures and vapors, at several reduced pressures and vapor forces. As the condensing surface subcooling increases in steady states, an abrupt change from drop type to film type occurs and the dropwise condensation curves of all the vapors become discontinuous at comparatively high vapor pressures, although the curves are continuous for propylene glycol and glycerol vapors at low vapor pressures. The surface subcoolings at the points, where these discontinuities start, are also shown and discussed.