An illuminator includes a first light source, a second light source, a first lens on which light emitted from the first and second light sources is incident, a second lens disposed in a downstream of the first lens, and a half wave plate. The first lens, the second lens and the half wave plate are arranged along a first axis. The first light source and the second light source are arranged along a plane perpendicular to the first axis. The half wave plate is disposed in the optical axis between the first lens and the second lens, the half wave plate being disposed in a position close to the second lens.