PURPOSE: To develop an electroless copper plating soln. capable of being regenerated and reused plural times by adding a fluorine-based nonionic surfactant and a cuprous complexing agent to the plating soln. contg. a copper salt and its complexing agent, a pH regulator and a reducing agent.

CONSTITUTION: The electroless copper plating soln. consists essentially of a copper ion source such as copper sulfate and copper nitrate, its complexing agent such as tartaric acid and its salt, EDTA or its salt, an alkali hydroxide such is NaOH and KOH for controlling the soln. to pH 11.5-13.0 and formaldehyde as the reducing agent for copper ion, and 0.01-2.8g/l of the fluorine based nonionic surfactant shown by formulas I and II, 0.001-1.75g/l of a cuprous complexing agent having an = N-C-C-N = group consisting of 2,2'-dipyridyl, phenanthroline and their derivative or 0.01-25g/l of a cyanide compd. such as NaCN are added to the plating soln.