A hydroponic system 1 is provided with a light collecting device 3 that has a pair of reflecting plates 31a vertically arranged parallel to cultivation surfaces 23 of cultivation panels 21 provided to hydroponic units 2. When natural light taken in through a light collection opening 30 propagates while being repeatedly reflected by reflecting surfaces facing the reflecting plates 31a seedlings p transplanted to the cultivation panels 21 are irradiated with light from emitting holes 32 provided in the reflecting plates 31a. Thus by taking in natural light objects to be cultivated can be grown efficiently and at low cost by taking natural light from the outside.
