The static contact angle of a liquid on a solid surface submerged in a second liquid is important because the attractive force of a liquid binder in wet agglomeration, the detergency process of a solid surface in liquid and the production of crude oil from porous subsurface rock by water displacement are affected by the wettability of the liquid to the solid surface in the second liquid, that is, mainly by the static contact angle of the liquid on the solid surface in the second liquid. It is known that the contact angle shows hysteresis and therefore differs depending on the measurement method. We experimentally investigated the hysteresis of the static contact angle of a polymer solid-water-liquid system. The hysteresis was evaluated by the difference between an advanced contact angle and a receded contact angle. The contact angle hysteresis of a polymer solid-water-liquid system became greater than that of a polymer solid-vapor-liquid system. The measurements of contact angle were compared with the values calculated by the use of extended Fowkes equation and Young-Dupre equation. Empirical equations showing contact angle hysteresis were obtained.