The objective of the study is to clarify the effect of vapor velocity on Marangoni condensation characteristics for water-ethanol bainary vapor mixture. The specially desingned heat transfer block having trapezoidal sectional area to concentrate the heat flux to the condensing surface with the notches near the sides of the surface was made to realize large heat flux with high precision of measurement. As a result of measurement, the condensation characteristic curves over a wide range of vapor velocity (0.3∼68 m/s) at three vapor concentration of ethanol (mass fractions of 0.09, 0.32 and 0.53) were revealed. Further, the effect of the departing drop diameter on the maximum heat transfer coefficient, which was the representative point of the heat transfer of Marangoni condensation, was clarified quantitatively.