We have been studying the method to prepare metal nano-particles in aqueous solution. We presented the role of low molecular compounds as a dispersing agent in aqueous solutions to synthesize silver particles at NIP27, last year. At NIP28 of this year, we would like to present the effect of PVA and polyacrylic acid compounds on the growth of silver particles. The PVA used in this experiment are as follows: Saponification ratio is 78.5-99.4 mol% and polymerization degree is 500-2600, where the saponification ratio is defined as the ratio of the number of OH group to total number of OH and COOCH₃ groups. The above both factors have affected the growth of silver particles and we have found in a series of our experiments that the PVA with the polymerization degree of 500 and the saponification ratio of 99.4 mol% has produced mono-dispersed silver particles of 10nm in average diameter. Furthermore, we have found that polyacrylic acid compounds as a dispersing agent have resulted in around 5nm in average diameter. Since this method to synthesized silver nano-particles does not use any organic solvents, we can avoid the problem regarding environmental pollution caused by organic fluids.