A semiconductor device, which is an insulated gate bipolar transistor, comprising: a first semiconductor layer of a first conductive type; a second semiconductor layer of a second conductive type formed in the vicinity of a surface first semiconductor layer; a third semiconductor layer of the second conductive type adjacent to the first semiconductor layer and formed in the vicinity of a surface of an opposite side of the second semiconductor layer; a fourth semiconductor layer first conductive type selectively formed on the third semiconductor layer; a trench penetrating through the fourth semiconductor layer and the third semiconductor layer into the first semiconductor layer; a gate insulating layer formed along an internal face of the trench; a first insulating layer formed in contact with the gate insulating layer in the trench; a gate electrode formed on a surface of the gate insulating layer; and an emitter electrode formed on a surface of the first insulating layer, wherein the gate electrode in the trench of at least one cross-sectional structure is divided by the first insulating layer and the emitter electrode, a width "a" of the trench is wider than a width "b" of an area in which the trench is not formed, the first insulating layer is formed in an active area of the semiconductor device, the gate electrode and the gate insulating layer are formed on a lateral face of the trench, and one side of the gate electrode is covered by the gate insulating layer and the opposite side of the gate electrode is covered by the first insulating layer, characterised in that a third insulating layer is formed on the first semiconductor layer in a termination area of the semiconductor device, the termination area comprises a region of the second conductivity type formed in the surface of the first semiconductor layer and connected to a floating electrode formed on the surface of the third insulating layer, the first insulating layer is thinner than the third insulating layer, and a thickness of the first insulating layer in the active area of the semiconductor device ranges from 300 nm to 1000 nm. a first semiconductor layer of a first conductive type; a second semiconductor layer of a second conductive type formed in the vicinity of a surface first semiconductor layer; a third semiconductor layer of the second conductive type adjacent to the first semiconductor layer and formed in the vicinity of a surface of an opposite side of the second semiconductor layer; a fourth semiconductor layer first conductive type selectively formed on the third semiconductor layer; a trench penetrating through the fourth semiconductor layer and the third semiconductor layer into the first semiconductor layer; a gate insulating layer formed along an internal face of the trench; a first insulating layer formed in contact with the gate insulating layer in the trench; a gate electrode formed on a surface of the gate insulating layer; and an emitter electrode formed on a surface of the first insulating layer, wherein the gate electrode in the trench of at least one cross-sectional structure is divided by the first insulating layer and the emitter electrode, a width "a" of the trench is wider than a width "b" of an area in which the trench is not formed, the first insulating layer is formed in an active area of the semiconductor device, the gate electrode and the gate insulating layer are formed on a lateral face of the trench, and one side of the gate electrode is covered by the gate insulating layer and the opposite side of the gate electrode is covered by the first insulating layer, characterised in that a third insulating layer is formed on the first semiconductor layer in a termination area of the semiconductor device, the termination area comprises a region of the second conductivity type formed in the surface of the first semiconductor layer and connected to a floating electrode formed on the surface of the third insulating layer, the first insulating layer is thinner than the third insulating layer, and a thickness of the first insulating layer in the active area of the semiconductor device ranges from 300 nm to 1000 nm.