ELECTRONIC COMPONENT ASSEMBLY, ELECTRONIC COMPONENT MODULE AND JUNCTION BOX

PROBLEM TO BE SOLVED: To provide an electronic component assembly which enables decrease in a dimension in a fitting direction of an external terminal connection part and an external terminal and downsizing of a holding member.SOLUTION: An electronic component assembly 1A comprises a substrate relay 10 and a bus bar substrate 2A to which the substrate relay 10 is electrically connected. The electronic component assembly 1A is housed in a housing part of a holding member 3A. The bus bar substrate 2A is formed in such a manner that a plurality of bus bars 4a-4d are attached to an insulating plate 5A by insert molding. The bus bars 4a-4d include external terminal connection parts 41, respectively, which are to fit female terminal fittings 9. The plurality of external terminal connection parts 41 and the substrate relay 10 are arranged in a direction that crosses a fitting direction of the external terminal connection parts 41 and the female terminal fittings 9. The fitting directions of the female terminal fittings 9 to the plurality of external terminal connection parts 41 are the same and the fitting direction is parallel with the bus bar substrate 2A.