The electrode cartridge for measuring an internal stress of a film of plating includes a cathode support, an anode support, a shield plate and an anode shell. The anode support supports an anode plate so that the anode plate is opposite to the cathode plate with a predetermined spacing. The shield plate is interposed between the cathode and anode plates. A through hole is made in the shield plate in such a manner that the through hole confronts a plating section and has a geometry which is reduced by a first predetermined scale factor relative to a geometry of the plating section. An opening is made in the anode shell in such a manner that the opening confronts the plating section and has a geometry which is magnified by a second predetermined scale factor relative to the geometry of the plating section.