To provide an effulgent coating material composition which has high designability and excellent material adhesiveness, above all adhesiveness specific to plastic substrates, and which can form coats having excellent physical coat properties such as weather resistance, etc. and a high ratio, within the coat, of raw ingredients derived from plants.

The provided effulgent coating material composition includes (A) a cellulose derivative with a number-average molecular weight of 55,000 or above consisting of at least one type selected from the group consisting of cellulose acetate butyrate and cellulose acetate propionate, (B) an acrylic resin, and (C) an effulgent pigment; in this effulgent coating material composition, the utilization ratio of the cellulose derivative (A) and acrylic resin (B) is confined, in terms of solid content mass ratio, to a range of 40/60-80/20, whereas the acrylic resin (B) includes a specified hydroxyl group-containing acrylic resin (B-1), whereas the content of the effulgent pigment (C) with respect to 100 pts.mass of the combined solid contents of (A) and (B) is 0.5-30 pts.mass.