In order to stabilize and obtain highly ion-conductive surface films, lithium metal was modified using two kinds of nonionic polyether-type surfactants, viz., poly(ethylene glycol) dimethyl ether and dimethyl silicone/propylene oxide copolymer in propylene carbonate (PC) and ethylene carbonate (EC) + dimethyl carbonate (DMC) solutions. Impedance spectroscopy indicated that the surface films formed in the presence of these surfactants were very stable, whereas that in the absence of surfactant was not. Scanning electron microscopy images showed that localized deposition is suppressed for the modified systems compared with the unmodified system. The mass change associated with the deposition-dissolution of lithium was investigated with cyclic voltammetry (CV) and quartz crystal microbalance (QCM) methods. The CV/QCM analyses indicated that the extent of inactive lithium is diminished markedly (by ca. 50% for PC and ca. 30% for EC + DMC solutions) and that the surface film was very stable and its thickness was apparently invariant due to the presence of the surfactants on the electrode surface. The QCM analysis also suggested that the surface-film may partly consist of the surfactant molecule constituents, including ethylene oxide (EO) groups reacted with lithium metal. It appears that a modified surface film including EO chains enhances the ionic conductivity, surface uniformity, and cyclability.