A method of manufacturing a quantum dot array having a plurality of oblique and parallel columnar parts each including at least one quantum dot on a substrate, the method comprising: a first step of obliquely vapor-depositing a material constituting a first barrier layer to become an energy barrier against the quantum dot with respect to a surface of the substrate, so as to form a plurality of the first barrier layers; a second step of obliquely vapor-depositing a material constituting the quantum dot with respect to the surface of the substrate, so as to form the quantum dots on the respective first barrier layers; and a third step of obliquely vapor-depositing a material constituting a second barrier layer to become an energy barrier against the quantum dot with respect to the surface of the substrate, so as to form the second barrier layers on the respective quantum dots, wherein the columnar parts extend obliquely with respect to the normal of a surface of the substrate, and extend in parallel to each other, wherein a deposition angle at which the deposition sources are positioned with respect to the normal of the surface of the substrate is at least 30° in the first, second, and third steps, and wherein the temperature of the substrate in the first step is 1/3 or less of the melting point of the material constituting the first barrier layers in terms of absolute temperature, the temperature of the substrate in the second step is 1/3 or less of the melting point of the material constituting the quantum dots in terms of absolute temperature, and the temperature of the substrate in the third step is 1/3 or less of the melting point of the material constituting the second barrier layers in terms of absolute temperature. a first step of obliquely vapor-depositing a material constituting a first barrier layer to become an energy barrier against the quantum dot with respect to a surface of the substrate, so as to form a plurality of the first barrier layers; a second step of obliquely vapor-depositing a material constituting the quantum dot with respect to the surface of the substrate, so as to form the quantum dots on the respective first barrier layers; and a third step of obliquely vapor-depositing a material constituting a second barrier layer to become an energy barrier against the quantum dot with respect to the surface of the substrate, so as to form the second barrier layers on the respective quantum dots, wherein the columnar parts extend obliquely with respect to the normal of a surface of the substrate, and extend in parallel to each other, wherein a deposition angle at which the deposition sources are positioned with respect to the normal of the surface of the substrate is at least 30° in the first, second, and third steps, and wherein the temperature of the substrate in the first step is 1/3 or less of the melting point of the material constituting the first barrier layers in terms of absolute temperature, the temperature of the substrate in the second step is 1/3 or less of the melting point of the material constituting the quantum dots in terms of absolute temperature, and the temperature of the substrate in the third step is 1/3 or less of the melting point of the material constituting the second barrier layers in terms of absolute temperature.