A method for producing an optical element having a three-dimensional structural part that can resolve problems associated with deterioration of optical characteristics that is caused by variations in the element shape in the conventional process and poor endurance caused by insufficient joining strength and the optical element produced by the method are provided. A method for producing an optical element configured by joining at least a first optical member and a second optical member formed from an oxide material includes the processes of forming a refractive index periodic structural part with a period equal to or less than a visible light wavelength on at least one of the first optical member and the second optical member, forming a joining layer composed of an oxygen-deficient oxide on the first optical member and the second optical member, tightly joining the first optical member and the second optical member by the joining layer, and oxidizing the joining layer after the tight joining.