Provided is a small resin-sealed electronic control device with a reduced plane area and volume, which can provide an enlarged area on which circuit components are mounted without increasing a plane area of electronic boards. In the resin-sealed electronic control device, a support member (20A) includes a first support plate (21a), a second support plate (22a), and a pair of rising portions (23a) which form a space portion with a first electronic board (30A) and a second electronic board (40A). An exterior covering material (11) is formed by injecting a melted synthetic resin into the space portion and spaces outside the space portion along the pair of rising portions (23a). Inner circuit components (33) are situated inside window holes formed through the support plate (20A) and face one of the first electronic board (30A) and the second electronic board (40A) opposed to each other with a gap interposed therebetween.