A semiconductor light emitting device includes a semiconductor stack including a first conductive semiconductor layer including a first surface, a second conductive semiconductor layer including a second surface opposite to the first surface, an active layer disposed between the first conductive semiconductor layer and the second conductive semiconductor layer, and a through hole disposed through the semiconductor stack. The semiconductor light emitting device further includes a contact layer connected to the first conductive semiconductor layer, disposed in the through hole, and disposed through the semiconductor stack, a first electrode layer connected to the contact layer, and a second electrode layer disposed on the second surface, and including a pad forming portion on which the semiconductor stack is not disposed. The semiconductor light emitting device further includes an insulating layer disposed between the first electrode layer and the second electrode layer, and an electrode pad disposed on the pad forming portion.