A wavelength conversion substrate according to one aspect of the present invention includes: a first substrate having an optical transparency; and a light modulation unit provided on one surface of the first substrate and configured to modulate a spectrum of incident light in accordance with a polarization state of the incident light. The light modulation unit includes: a plurality of metallic structures periodically provided at intervals from one another on one surface of the first substrate and configured to exhibit plasmon resonance due to incident light; and a plurality of wavelength conversion units provided so that at least some wavelength conversion units are adjacent to the plurality of metallic structures and comprising a wavelength converting material configured to emit light in a wavelength band different from a wavelength band of the incident light.