A light-emitting device includes: a first planar member having a plurality of light sources; a second planar member being parallel to the first planar member; and a reflecting member reflecting light beams from the respective light sources to the second planar member, the reflecting member being provided on an inner side of a polygon which is defined by the light sources as vertices thereof, wherein the reflecting member having a polygonal pyramidal shape with a bottom surface being parallel to the first planar member satisfies at least one of: a condition that a diffusion distance is from 0.8 to 1.3 when a length of each side of a polygon of the bottom surface is 1; and a condition that an angle between a side surface of the polygonal pyramid and the bottom surface is from 40 degree to 60 degree.