PURPOSE: To obtain a pattern forming method in which a pattern superior in long-term durability without a need to be repainted is formed on a concrete surface.

CONSTITUTION: In a prepared decorative mat 1, a plurality of colored granular materials 6 are distributed on a projected and recessed pattern transfer surface 4 through an adhesive layer 5 which is reduced in adhesive power by absorbing water. The projected and recessed pattern transfer surface 4 of the decorative mat 1 serves as a contact surface with a concrete surface, and a concrete material is formed. The adhesive power of the adhesive layer 5 is reduced by the water content of the concrete material. The colored granular materials 6 are migrated to the concrete surface to be embedded therein. The concrete surface has a projected and recessed pattern by the transfer of the projected and recessed pattern transfer surface 4.