A planar light source includes a light guide member including light-emitting units separated by a groove and one or more light sources disposed in one or more of the light-emitting units. The light-emitting units include outer portions and at least one inner portion located in a region surrounded by the outer portions in a plan view. In the plan view, at least one of the outer portions is adjacent to a smaller number of light-emitting units than a number of light-emitting units to which one of the at least one inner portion is adjacent. In a state in which the same power is supplied and one of the outer portions and one of the at least one inner portion are allowed to individually emit light, brightness of the one of the outer portions is higher than brightness of the one of the at least one inner portion.