The present invention relates to a colloidal metal solution comprising colloidal metal particles with a sulfur compound of low molecular weight such as mercaptoacetic acid, mercaptopropionic acid, mercaptoethanol, etc. as a protective colloid on the particle surfaces and having a pH of 8-14. According to the present invention, a colloidal metal solution having a high concentration and a distinguished dispersion stability with a small amount of the protective colloid can be provided with a commercially and economically high advantage without any operation such as centrifuge, etc.