A light modulation element unit includes a light modulation element having a light modulator configured to modulate incident light and a cover glass that covers a light incident surface of the light modulator, a light shielding member, disposed along a surface of the cover glass, which has an opening in which light going to the light modulator passes and a light shield configured to shield light that does not pass the opening, and a heat radiation member provided in a direction different from a direction of the cover glass with respect to the light modulation element. The light shielding member has an extension that extends to outside of the cover glass and faces the heat radiation member. A first gap between the extension and the heat radiation member is smaller than a second gap between the light shield and the surface of the cover glass.