A planar light-emitting device allowing for high luminance uniformity has a plurality of light-emitting units (4), each including a lightguide plate (3) having a light-exiting surface, an opposite surface opposite to the light-exiting surface, a peripheral side surface extending between the respective peripheral edges of the light-exiting surface and the opposite surface, and a light-entrance surface (3a) defined by a part of the peripheral side surface. Each light-emitting unit further includes a light source (2) adjacently disposed to face the light-entrance surface to emit light into the lightguide plate through the light-entrance surface. The light-emitting units are arranged in a plurality of mutually adjacent rows with the light-exiting surfaces (3a) of their respective lightguide plates being substantially flush with each other. Adjacent rows of the light-emitting units are displaced relative to each other in the direction of the rows.