PURPOSE: To obtain a safe electroless gold plating soln. having high stability and a long life and causing no environmental pollution by adding a water soluble gold salt, a pH adjusting agent, a reducing agent for gold ions and an acetonitrile deriv. as a complexing agent for gold ions.

CONSTITUTION: When an electroless gold plating soln. contg. a water soluble gold salt, a complexing agent for gold ions, a pH adjusting agent and a reducing agent for gold ions is prepd., an acetonitrile deriv. such as HOCH2CN or NH2CH2CN is added as the complexing agent without using cyanide ions. A very safe and hygienic electroless gold plating soln. having high stability and a long life and causing no environmental pollution is obtd.