In a trench-gate-type insulated gate bipolar transistor, a current will not flow down to a lower portion of a trench, a high electrical field at the lower portion of the trench is suppressed even if a high voltage is applied, such as at a time of turning off, an increase in on-state resistance and a decrease in breakdown resistance and withstand voltage are suppressed. In the semiconductor device, a plurality of trenches is disposed to reach a rear surface of a drift layer, and a collector layer is disposed at a tip end side in an extended direction of the trenches in a surface layer portion of the drift layer. When a gate electrode is applied with a predetermined voltage, a channel region is formed in a portion of the base layer contacting the trenches, and an electric current flows in the predetermined direction along the trenches.