Electronic circuit device (100) is structured so that a substrate module unit that are formed by stacking substrate modules made of a first resin sheet with electronic component (190) embedded thereinto is inserted into housing (150) including connecting terminal (120), control circuit (130), and first wiring pattern (140), where the substrate modules are connected to each other electrically and mechanically. This electronic circuit device (100) dispenses with a mother substrate. Further, with slimming down of a substrate module, a substrate module unit with a large number of substrate modules stacked can be loaded in a limited packaging space, thus mounting greater storage capacity and higher functionality.