A metallic film and a grounding pattern are surely connected to each other so as to achieve electrical shield of an electronic circuit unit. In an electronic circuit unit, the metallic film is provided on a top surface of a sealing resin portion for burying an electronic component, the side surfaces of the sealing resin portion that are opposite to each other, and the side surfaces of the multi-layered substrate that are opposite to each other. The metallic film is connected to the grounding patterns that are provided on the top surface of the multi-layered substrate or between the laminated layers of the multi-layered substrate. Therefore, it is possible to achieve a superior electrical shielding effect through the metallic film, as compared with the related art. Since the metallic film is formed on the side surfaces of the sealing resin and the side surfaces of the multi-layered substrate, when the metallic film is formed by a plating method, the blind hole may not be provided in the related art. Therefore, it is possible to achieve the superior circulation of the plating liquid, which results in sure connection between the sure connection between the grounding pattern and the metallic film.