PURPOSE: To minimize positional displacement of circuit board of each internal layer by boring holes to the reference mark formed at the outside of product at the time of processing a circuit and using such holes as the reference holes for integrating laminated layers.

CONSTITUTION: A photosensitive dry film is laminated to a copper extended laminated plate 4 for internal layer and a pairing internal mask film 2 is attached at the spacer area 3, a copper extended laminated layer 4 is provided between the films and these are baked to form a circuit board 12 for internal layer. In this case, the reference marks 1 are also formed at the predetermined positions. The reference marks 1 are read by a punching machine and the reference holes 8 are provided in the predetermined position. The reference holes are punched on the copper extended laminated plate 11 for external layer and prepleg 13. The circuit board of internal layer, copper extended laminated plate for external layer and prepleg are stacked, guide pins are inserted into the reference holes to integrate the laminated layers.