[Object] A semiconductor device is configured to release heat from semiconductor chips more efficiently. [Means for Solution] A semiconductor device includes: a die pad 11 which has a die pad main surface 111 and a die pad rear surface 112; a semiconductor chip 41 mounted on the die pad main surface 111; a sealing resin portion 7 formed with a recess 75 for exposure of the die pad rear surface 11 and covering the die pad 11 and the semiconductor chip 41; and a heat releasing layer 6 disposed in the recess 75. The recess 75 has a recess groove 753 outside the die pad 11 in a direction in which the die pad rear surface 112 extends, and the recess groove 753 is closer to the die pad main surface 111 than to the die pad rear surface 112. The heat releasing layer 6 has a junction layer which is in contact with the die pad rear surface 112 and having part thereof filling the recess groove 753.