An insulated-gate bipolar semiconductor device, comprising: a semiconductor substrate of an intrinsic characteristic or a first conductivity type; a trench provided at a first main surface of the semiconductor substrate; a ladder-shaped emitter region of the first conductivity type formed at a part of a first main surface of the semiconductor substrate along the lengthwise direction of the trench; a first impurity region of a second conductivity type formed on a second main surface of the semiconductor substrate; a second impurity region (4, 6) of the second conductivity type formed to surround the emitter region of the first conductivity type as a base region; a control conductor formed in said trench at a part of the second impurity region (4, 6) of the second conductivity type with an insulating film therebetween; an insulating layer covering the first main surface of the semiconductor substrate except for a contact hole region; a first main electrode provided in contact with both the emitter region of the first conductivity type and the second impurity region (4, 6) of the second conductivity type in said contact hole region; a second main electrode provided in contact with the first impurity region of the second conductivity type; and a control electrode connected to the control conductor, wherein the first main electrode runs in the lengthwise direction of the trench and spans the portions between the cross-pieces of the ladder-shaped emitter region, such cross-pieces providing a direct electrical contact between the emitter region and the first main electrode and such portions between the cross-pieces being of the second conductivity type and having a high impurity concentration and serving to electrically connect the second impurity region (4, 6) to the first main electrode, regions (14, 15) to increase the specific resistance of portions of the emitter region are formed in the vicinity of a surface of the emitter region between the cross-pieces and the trench in order to form an emitter ballast resistance, wherein the resistance of the emitter region in a direction in parallel to the trench is sufficiently lower than the resistance of the emitter region in a direction perpendicular to the trench in order to restrain unbalance in the element operation, so that the electric resistance between the first main electrode and a part of the emitter region of the first conductivity type that is close to the control conductor has a prescribed value, which is independent from the distance of said part of the emitter region close to the control conductor to the emitter region in direct electrical contact with the first main electrode. a semiconductor substrate of an intrinsic characteristic or a first conductivity type; a trench provided at a first main surface of the semiconductor substrate; a ladder-shaped emitter region of the first conductivity type formed at a part of a first main surface of the semiconductor substrate along the lengthwise direction of the trench; a first impurity region of a second conductivity type formed on a second main surface of the semiconductor substrate; a second impurity region (4, 6) of the second conductivity type formed to surround the emitter region of the first conductivity type as a base region; a control conductor formed in said trench at a part of the second impurity region (4, 6) of the second conductivity type with an insulating film therebetween; an insulating layer covering the first main surface of the semiconductor substrate except for a contact hole region; a first main electrode provided in contact with both the emitter region of the first conductivity type and the second impurity region (4, 6) of the second conductivity type in said contact hole region; a second main electrode provided in contact with the first impurity region of the second conductivity type; and a control electrode connected to the control conductor, wherein the first main electrode runs in the lengthwise direction of the trench and spans the portions between the cross-pieces of the ladder-shaped emitter region, such cross-pieces providing a direct electrical contact between the emitter region and the first main electrode and such portions between the cross-pieces being of the second conductivity type and having a high impurity concentration and serving to electrically connect the second impurity region (4, 6) to the first main electrode, regions (14, 15) to increase the specific resistance of portions of the emitter region are formed in the vicinity of a surface of the emitter region between the cross-pieces and the trench in order to form an emitter ballast resistance, wherein the resistance of the emitter region in a direction in parallel to the trench is sufficiently lower than the resistance of the emitter region in a direction perpendicular to the trench in order to restrain unbalance in the element operation, so that the electric resistance between the first main electrode and a part of the emitter region of the first conductivity type that is close to the control conductor has a prescribed value, which is independent from the distance of said part of the emitter region close to the control conductor to the emitter region in direct electrical contact with the first main electrode.