To provide a decorative aggregate washout sheet for manufacturing a concrete product by making all decorative aggregates project from the surface of a concrete and at the same time, making the tips of the decorative aggregates continuously flush with each other as well as supply this concrete finished product at a low cost.

This decorative aggregate washout sheet 1 contains a support sheet 2 and a decorative aggregate 3, and the support sheet 2 comprises a raw material 21 for the sheet 2 and a layer 22 to which a pressure-sensitive adhesive containing a concrete curing retarder is applied. Both concrete curing retarder and pressure- sensitive adhesive are a combination of such agents as not to impede with each other in their mutual action. The decorative aggregates 3 are bonded to the surface of the support sheet 2, in such a manner that the aggregates 3 are flush with each other, with the help of the pressure-sensitive adhesive. The concrete curing retarder penetrates the desired depth of a mortar or a concrete layer after oozing out of the layer 22 following the formation of the mortar or the concrete layer, and retards the curing of the mortar or the concrete layer.