A semiconductor device includes IGBT devices; and a freewheeling diode provided for each IGBT device. The IGBT devices are connected in parallel to be driven. Each IGBT device includes: a collector region; a drift region; a body region; a trench gate penetrating the body region; and an emitter region surrounded by the body region and in contact with the trench gate. Each IGBT device further includes an active cell with the emitter region; a dummy cell without the emitter region; and an active dummy cell without the emitter region. The active dummy cell has a float cell where the body region is in electrically-floating condition. A ratio of the number of float cell to the total number of the active cell and the active dummy cell is larger than or equal to 5% and is smaller than or equal to 35%.