A semiconductor device including quantum dots comprises a barrier layer of a semiconductor crystal having a first lattice constant and a quantum dot layer including a plurality of quantum dots of a semiconductor crystal having a second lattice constant formed on the barrier layer and a side barrier layer of a semiconductor crystal having a third lattice constant, which is formed in contact with the side faces of the plurality of quantum dots, in which the barrier layer, the quantum dots and the side barrier layer are configured so that the difference between the values of the first lattice constant and the second lattice constant has a sign opposite to that of the difference between values of the first lattice constant and the third lattice constant.