A hydroponic system 1 is provided with a light-collecting apparatus 3 having a pair of reflecting plates 31 a that are vertically arranged in parallel with a culture surface 23 of a culture panel 21 of a hydroponic unit 2. During a process in which natural light taken from a light-collecting opening 30 propagates while repeatedly reflected by opposing reflecting surfaces of a reflecting plates 31 a, by allowing seedlings p that are transplanted into the culture panel 21 to be irradiated with the light through a light-emitting hole 32 bored in the reflecting plate 31a, a culture object can be grown efficiently at a low cost by taking natural light from the outside.
