PURPOSE: To enable to form an electroless copper plating film with excellent release strength on an epoxy resin substrate by a method wherein an epoxy resin substrate is treated by an aqueous cupric chloride solution and, thereafter, treated by an aqueous water-soluble peroxide solution.

CONSTITUTION: In carrying out electroless copper plating after a sensitizing treatment is applied to an epoxy resin substrate, an epoxy resin substrate is firstly treated by an aqueous solution containing cupric chloride and, thereafter, by an aqueous solution of a water-soluble peroxide. As an aqueous solution containing cupric chloride, the use of an aqueous 20W40% cupric chloride solution is preferred and, as a water-soluble peroxide, hydrogen peroxide, sodium perborate, sodium percarbonate or the like are mentioned. In case of an epoxy resin substrate having a copper coating or a copper plating layer, e.g., a waste epoxy resin substrate with printed circuit, a copper layer is removed by cupric chloride treatment and an epoxy resin substrate can be regenerated and reused.