PURPOSE: To form the tone like a natural stone by forming the film thickness in the peripheral sections of plastic chips of a colored bonding agent layer thicker than the film thickness of other sections and rolling mainly non-imbedded sections of the colored bonding agent layer on the colored bonding agent layer of the peripheral sections of plastic chips.

CONSTITUTION: When a colored bonding agent layer 2 is formed in even thickness on one face of a transparent film 1 and plastic chips 3a and 3b are scattered over the colored bonding agent layer 2, the chips are settled partly into the bonding agent layer 2 by their own weight and imbedded therein, and also swellings 2a are generated in the bonding agent layer by surface tension on the chip peripheral sections. When the same is dried in said state, the thickness of the bonding agent layer is made approximately half all over. At that time, as the drying speed of the chip peripheral sections 2a is fast, a pigment in the bonding agent layer is pulled from the peripheral sections into said sections 2a, and the concentration of said sections 2a gets higher to make the difference of color phase large. The bonding agent layer 2 is dry fixed, and then mainly non-imbedded sections of the bonding agent layer of chips 3a and 3b are rolled, and said rolled sections 3c and 3d cover the bonding agent layer sections on the peripheries of chips.