PURPOSE: To prevent an occurrence of wrinkles in a metal foil by a method wherein laminates each obtained by overlapping circuit boards through a prepreg and disposing a metal foil on each outer surface thereof through a prepreg are overlapped alternately with molded plates and pressure molded through cushioning materials, and the compressed amount of the cushioning materials generated at this time is determined to be within a specific range.

CONSTITUTION: A laminate 3 is obtained by overlapping circuit boards 7 provided with inner circuits 6 through a prepreg 8 and disposing a metal foil 5 on each outer surface thereof through a prepreg 8. The laminates 3 are overlapped alternately with molded plates 2 and clamped between hot plates 4 through cushioning materials 1 to be molded under heat and pressure. The thickness (lap number) of the cushioning materials 1 is determined so that the total reduction amount of the cushioning materials 1 in thickness generated at the time of pressur molding is within 15-35% of the total thickness of the inner circuits 6. As the metal foil 5, a copper foil not more than 20μm in thickness is preferably used.