To provide a process for removing easily an oily component-containing deposit on a solid surface with an aqueous liquid such as water.

A process for removing an oily component-containing deposit on a surface of a solid, comprises imparting previously, to the solid surface, the characteristic of having a water affinity equal or above in comparison with that of the oil component-containing deposit to be removed off by using a material containing a water-soluble component and supplying an aqueous liquid around the deposit on the solid surface. The water-soluble component is desirably an alkaline component.