In an electronic circuit device including a substrate including a front surface on which an electronic circuit element is mounted and a reverse surface opposite to the front surface in a thickness direction of the substrate, an electrically conductive terminal member electrically connected to the electronic circuit element, a lead frame extending perpendicular to the thickness direction to face the reverse surface in the thickness direction, and a sealing resin covering at least partially the electronic circuit element, substrate and lead frame while at least a part of the electrically conductive terminal member is prevented from being covered by the sealing resin, the substrate extends to project outward from an end of the lead frame in a transverse direction perpendicular to the thickness direction while the end of the lead frame is covered by the sealing resin.