A semiconductor device comprises a transparent insulating substrate, a first insulating layer, a semiconductor layer, a second insulating layer, and an island-like semiconductor layer in order from the side of the substrate. When the laser light is irradiated from the upper side of the semiconductor device the laser light irradiated to the portions having no island-like semiconductor layer thereon is absorbed by the semiconductor layer after being transmitted through the second insulating layer and the heat generates in the semiconductor layer. Heat diffusion occurs thereafter. At the same time, the energy of laser light by laser radiation from the upper side of the semiconductor device is absorbed in the island-like semiconductor layer. The energy is accumulated as the heat in the island-like semiconductor layer and the second insulating layer to suppress the heat diffusion into the substrate.