To provide a composite plating method capable of making dispersed particles dispersed in a plating bath into a form of microscopic particles finer than a nanocrystal of matrix metal and of codepositing the particles in the state of being dispersed in the nanocrystal grain boundary in the matrix metal.

The composite plating method of dispersing the dispersed particles in the plating bath of the matrix metal and codepositing the particles with the matrix metal includes the steps of: dispersing in the plating bath the dispersed particles consisting of metal oxide capable of phase transformation; phase transforming the dispersed particles by plating potential; and fining the dispersed particles in the plating bath by the strain due to the phase transformation, thereby codepositing the particles with the matrix metal.