To provide a printed circuit board wherein a thermally protected component can be thermally protected without lowering the temperature of a heating component to the same level as the temperature of the thermally protected component.

In the multilayer printed circuit board (PCB), a heating component (101) that operates at a first proof temperature (TS1), and a thermally guaranteed component (102) that operates at a second proof temperature (TS2) lower than the first proof temperature (TS1), are mounted over a first single-layer substrate (S1a). Second single-layer substrates (S2a, S4a) are provided with first solid layers (LG1a, LP1a) and second solid layers (LG2a, LP2a). When the second single-layer substrate is laid on the first single-crystal substrate (S1a), the first solid layer is positioned under the heating component (101) and the second solid layer is positioned under the thermally guaranteed component (102).