An electronic circuit board includes: electronic components； a silicon board that is plate shaped, includes a wiring pattern provided on at least one of a surface and a reverse surface thereof, and includes recessed portions where the electronic components are individually mounted； and a supporting board that is layered over the reverse surface of the silicon board, and includes a wiring pattern provided on at least one of a surface and a reverse surface thereof. Side faces of the recessed portions are perpendicular to the surface of the silicon board, the wiring pattern is connected to at least one of the electronic components mounted in the recessed portions, via at least one of a via and a bottom surface electrode provided in of the at least one of the recessed portions, and the recessed portions penetrate through the silicon board.
