Provided is a diffractive optical element that is thin and is capable of radiating in a wide range while further reducing zero-order light. This diffractive optical element is provided with: a substrate; an uneven part for causing a predetermined diffraction effect on incident light, the uneven part being provided on one surface of the substrate; and an antireflective layer provided between the substrate and the uneven part; the refractive index difference in the wavelength band of incident light between a first medium constituting projections in the uneven part and a second medium constituting recesses therein being 0.70 or greater, and the emission angle range, which is a range indicating the spread of an optical pattern formed by diffracted light emitted from the uneven part when incident light is incident from the direction of a line normal to the substrate, being 60° or greater.