To place concrete simultaneously when an irregular pattern is formed and colored by a method wherein a concrete hardening retarder layer is formed on a sheet surface, and many colored glandular material are stuck by distribution onto that to form a pattern.

By a series of processes, a colored granular material 3 is transferred to be buried in a surface of a concrete product 21 to form a colored pattern. Further, under this state, a most front surface of the colored pattern 22 of the obtained concrete product 21 comes in contact with a retarder layer, hardening is restrained or delayed by its action, and a soft unhardened surface layer is formed. Then high pressure water or the like is sprayed onto the concrete product 21 to expose aggregate by washing, and the concrete of the unhardened surface layer is removed to form an unhardened surface layer removed part 24. The colored pattern 22 wherein the colored granular material 3 is buried in the surface is formed onto the concrete produce 21. Then, the most front surface of the colored pattern 22 is formed into the unhardened surface removed part 24 owing to exposing aggregate by washing.