An illuminator is provided including: a light source unit composed of a point light source; a light guide plate including an incidence surface into which light emitted from the light source unit is introduced, and an exit surface out which the light that has been introduced from the incidence surface exits; and a prism body where a plurality of prisms are arranged so as to refract the light that has exited out from the exit surface of the light guide plate, wherein the prism body is arranged at a specific area on the entire exit surface of the light guide plate so as to refract part of the light that has exited out from the exit surface of the light guide plate.