The present invention relates to composite polymers containing nanometer-sized metal particles and manufacturing method thereof, which can be uniformly dispersed nanometer-sized metal particles into polymers, thereby allowing the use thereof as optically, electrically and magnetically functional materials. The method for manufacturing composite polymers containing nanometer-sized metal particles includes the steps of: dispersing at least one metal precursor into a matrix made of polymers in a molecule level; and irradiating rays of light on the matrix containing the metal precursors dispersed in the molecule level and reducing the metal precursors into metals and fixing nanometer sized metal particles inside of matrix.