A lighting device includes a first light guide area sandwiched between partitions extending along a first direction, a first light emitting element emitting light in a first wavelength band, and a semi-transmitting reflective film covering the first light guide area, the first light guide area including a first protrusion, and a reflective film covering the first protrusion and each side of the partitions, the first light guide area including, a first part having a constant first width in a second direction crossing the first direction, and a second part adjacent to the first part and the first width decreasing as it recedes from the first part, wherein the first light emitting-element is arranged in the second part.