Upon the manufacture of a non-leaded type semiconductor device having an encapsulater, and a gate cured resin and air vent cured resins which remain as a result of the exposure of leads and tub-suspension leads to a mounting surface of the encapsulater and the formation of the encapsulater, a groove through which a resin flows is not provided over the full circumference of a cavity defined in a mold die for forming the encapsulater. A gate and air vents are provided outside an area in which no groove is defined. The flow of the resin between the cavity and each of the gate and air vents is made through a gap or space defined between each of the adjacent leads and each tub-suspension lead. If the leads and the tub-suspension leads are cut at a groove-free place, then the occurrence of resin waste and a resin crack can be restrained because the gate cured resin and the air vent cured resins have their surfaces which are flat and level with the leads and the tub-suspension leads.