A light source apparatus includes a light source, a light guide plate, a plurality of optical sheets, and an adhesive material. The light guide plate has an incident surface on which light from the light source is incident, and a light emitting surface from which the light on the incident surface is emitted. The plurality of optical sheets are disposed to overlap one another on the light emitting surface. The adhesive material fixes positions of the plurality of optical sheets. The plurality of optical sheets include respective extension portions each formed by bending an extension of a peripheral portion of the optical sheet to face a side surface of the light guide plate. The respective extension portions are aligned with displacements so as not to completely overlap one another, and the adhesive material is applied to the respective extension portions.