A light source device includes a phosphor layer having a side surface, a bottom surface, and a top surface opposed to the bottom surface, a reflecting member opposed to the side surface of the phosphor layer, a substrate disposed on the bottom surface side of the phosphor layer, and an adhesive adapted to bond the phosphor layer and the substrate to each other. A surface of the substrate located on the phosphor layer side includes a recessed section overlapping the reflecting member on at least an outer side of the phosphor layer in a planar view. A part of the adhesive running off the phosphor layer is received by the recessed section. Fluorescence generated in the phosphor layer is emitted from the top surface and the side surface.