A hydroponic system (1) is provided with a light-collecting apparatus (3) having a pair of reflecting plates (31a) 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 (31a), 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.
