A semiconductor device package includes a semiconductor chip including a conductive pad, a die pad on which the semiconductor chip is mounted and having a first thickness, a lead pattern including a first portion disposed adjacent to the edge of the die pad and having the first thickness and a second portion having a second thickness greater than the first thickness, a heat radiation member disposed on the die pad and the lead pattern and including a groove formed at its bottom surface, and a conductive line disposed to electrically connect the conductive pad to the lead pattern corresponding to the conductive pad and partially inserted into the groove.