[Problem] To provide a multi-tiered shelf type plant growth device, which can efficiently radiate heat from artificial illuminators into the atmosphere and prevent temperature increases in a nutrient solution flowing in trays directly on top of the artificial illuminators and in the root region of plants placed on the trays, and a plant growth system having this multi-tiered shelf type plant growth device. [Solution] Multi-tiered shelf type plant growth devices (3 - 6) have artificial illuminators (13) provided on the lower surface of each shelf, each artificial illuminator (13) being provided with: a box (13a) provided on the lower surface side of a irrigation tray (31) of a respective shelf； florescent lamps (13c)； and power supply units (13g). The power supply units (13g) are provided on a bottom plate (13e) of the box (13a), and a top plate (13d) and the power supply units (13g) are spaced away from each other. The bottom plate (13e) also serves as a reflective plate for the fluorescent lamps (13c).
