Since it has been pointed out that liquid Zn alloy sometimes exhibits non-wetting behavior on high-tensile strength steels usually containing Si and Mn, there have been several studies to improve the wettability of liquid Zn. Although those studies evaluated the wettability qualitatively by observation of the surface of galvanized steels or exfoliation testing of Zn on steel substrates, it is further required to evaluate the wettability of liquid Zn on steels by measuring the contact angle, work of adhesion, spreading velocity etc. which are usually used to assess the general wetting behavior. In the present work, we applied a sessile drop method to measure the change in contact angle and diameter of liquid Zn droplets wetted on steels containing Si and Mn with time to evaluate quantitatively the dynamic wetting behavior of liquid Zn on steel substrates.