Highly concentrated pastes of Au and Ag nanoparticles were prepared by a novel method using a comb-shaped block copolymer and an amine as protective colloid and reducing agent, respectively. The nanoparticles were applied to paint colorants utilizing the surface plasmon light absorption. Au and Ag nanoparticles exhibited clear red and yellow colors, respectively. It was revealed that the nanoparticles possess aesthetic color properties such as transparency and color saturation as well as excellent weather durability. Further, a novel metal paint system was also developed from using the condensed Ag paste, which enables us to produce metal like coatings by a simple, dry and environmentally friendly process.