To obtain composite particles contained in a dispersion having the lowest membrane-forming temperature at a specific temperature or lower, capable of forming a coated membrane excellent in weather resistance, especially in soil resistance by making exist a polymer on the surface of polymer particles.

The composite particles are obtained by making exist at least either one of a polymer of an organic silicon compound or a polymer of an organic metal compound on the surfaces or in the vicinity of the surfaces of polymer particles [preferably polymer particles having 1-29°C glass transition temperature, e.g. (meth)acrylic polymer particles], and having ≤90°C lowest membrane-forming temperature. Further, it is preferable that the above existing polymer is chemically bonded to the polymer particles, and also, the amount of the existing polymer based on the polymer particles is 0.5-100 pts.wt. based on 100 pts.wt. polymer particles. The composite particles can be prepared as a dispersion by dispersing them in a poor solvent. A coated membrane formed from the dispersion is excellent in weather resistance and soil resistance.