To provide a decorated surface forming method which is applicable to the surface of an inner or outer wall of a building and by which natural feeling like natural earth can be expressed by restraining the finished appearance from having a wet color.

The decorated surface is formed by a step (1) to apply a coating material containing a water-soluble resin and aggregate to a base material to form a decorated layer, a step (2) to absorb the water-soluble resin on the surface of the decorated layer by attaching/detaching a liquid absorbing tool having a liquid absorbing material built-in to/from the surface of the decorated layer before the decorated layer is dried and a step (3) to dry the decorated layer.