It is intended to provide a plant growth system wherein light sources are located close to plants so as to efficiently ensure a sufficient amount of light for the plants to grow and simultaneously ensure air flow, thereby providing a favorable growth environment for the plants. In a plant growth chamber, there are provided multiple shelf parts for irradiating the plants with light for the growth, a cover surrounding the light sources wherein multiple ventilation bores are formed on a plant-facing face of a transparent light-permeable wall, an air inlet that opens in the space within the cover for sucking the air in the space, and a circulation channel that cools down the air sucked through the air inlet and blows out the sucked air into the plant growth chamber.