Provided is a lighting device for a plant factory, which has a lighting unit (11) that captures natural light and a light-emitting unit (12) that irradiates light captured by the lighting unit to inside a plant factory, and which comprises a light-reflecting layer comprising silver or a silver alloy on the inside surface thereof. The lighting device for a plant factory is characterized by the light captured by the lighting unit (11) being reflected at least once by the light-reflecting layer and then being irradiated inside the plant factory from the light-emitting unit (12), and by the near infrared light quantum ratio for 700-1,000 nm wavelengths in light irradiated inside the plant factory from the light-emitting unit (12) being at least 40%.
