PURPOSE: To directly process an element or conductor pattern on an internal layer, process-operate with high precision, and have a mounting structure with high density by a method wherein the element or conductor pattern formed on the internal layer of a module substrate is peeped through a hole which is provided in the module substrate.

CONSTITUTION: A plurality of module substrates 22 are laminated to form a conductor pattern on a vertical surface and between respective layers. Circuit elements 27, 28 are mounted into the inside on an upper surface and also a film resistor element 29 is formed on an upper surface of a module substrate 22-2 on a second layer. A hole 31 for this film resistor element 29 is provided so as to penetrate a module substrate 22-1 on a first layer. Next, one electrode lead 35 of the circuit element 27 mounted on an upper surface is inserted into a hole 36 penetrating the module substrate 22-1 on a first layer, and another electrode lead 35 is inserted into a hole 41 penetrating the module substrates 22-1, 22-2 on the first and second layers, and each is directly connected to the conductor pattern with solder 43 on a following module substrate.