To provide the surface treatment method by which a lightweight cellular concrete panel, that has excellent surface tensile strength and causes no peeling-off or no falling-off of a finishing layer such as coating layer, can stably and efficiently be produced in a short time.

In this surface treatment, the surface of a lightweight cellular concrete panel having a bulk specific gravity in absolute dry condition of ≤0.6 is coated with an aqueous resin emulsion in a 0.1 to 0.5kg/m2 coating weight to strengthen the surface of the panel. At this time, at least cut or cut-off surfaces of the lightweight cellular concrete panel are coated with the aqueous resin emulsion, which contains a resin component consisting of at least one kind of resin selected from among acrylic resins, epoxy resins, styrene resins and methane resins, and has ≤10dPa.s viscosity and 3 to 20wt.% resin solid content. Also, after coating the surface of the concrete panel with the aqueous resin emulsion, the resulting surface is further subjected to filler coating and/or adhesive coating.