Abstract: A lighting device (20) included in a plant cultivation device (10) includes: a light source unit (25) including an LED serving as a light source; and a cooling unit (30) including a cooling section (21) which allows a cooling medium to flow therein, the cooling unit (30) cooling the light source by heat exchange between the cooling medium supplied to the inside of the cooling section (21) and the light source unit (25). A fan (26) provided in the cooling unit (30) starts and stops supply of the cooling medium in accordance with the temperature (T) measured by a light source temperature sensor (27) provided to the light source unit (25). This makes it possible for a lighting device for plant cultivation and a plant cultivation device to reduce formation of condensation during cooling of the light source, while achieving efficient cooling of the light source.