A plant cultivation device, comprising: a cultivation tank for growing a plant; and a solar heat pump system comprising: a water tank for supplying cultivation water to the cultivation tank via a watering channel and for suctioning cultivation water from the cultivation tank via a water-sucking pipe; a heat-collecting part having an air-storage part that communicates with an upper section of the water tank, wherein the heat-collecting part receives sunlight and causes pressure of air heated inside the air-storage part to press a surface of water inside the water tank, the water tank supplies the cultivation water that has been pressed by the air to a culture medium material arranged inside the cultivation tank from above through the watering channel, the heat-collecting part causes the surface of water inside the water tank to be raised as a result of the heated air being cooled by a decrease of the sunlight, and the water tank suctions the cultivation water from a bottom section of the cultivation tank via the water-sucking pipe in accordance with rising of the cultivation water; characterized in that the cultivation water circulates between the cultivation tank and the pump system; the solar heat pump system comprises a discharge check valve that prevents backflow of the cultivation water supplied from the water tank to the cultivation tank; and a suction check valve that prevents backflow of the cultivation water suctioned from the cultivation tank to the water tank. a cultivation tank for growing a plant; and a solar heat pump system comprising: a water tank for supplying cultivation water to the cultivation tank via a watering channel and for suctioning cultivation water from the cultivation tank via a water-sucking pipe; a heat-collecting part having an air-storage part that communicates with an upper section of the water tank, wherein the heat-collecting part receives sunlight and causes pressure of air heated inside the air-storage part to press a surface of water inside the water tank, the water tank supplies the cultivation water that has been pressed by the air to a culture medium material arranged inside the cultivation tank from above through the watering channel, the heat-collecting part causes the surface of water inside the water tank to be raised as a result of the heated air being cooled by a decrease of the sunlight, and the water tank suctions the cultivation water from a bottom section of the cultivation tank via the water-sucking pipe in accordance with rising of the cultivation water; a water tank for supplying cultivation water to the cultivation tank via a watering channel and for suctioning cultivation water from the cultivation tank via a water-sucking pipe; a heat-collecting part having an air-storage part that communicates with an upper section of the water tank, wherein the heat-collecting part receives sunlight and causes pressure of air heated inside the air-storage part to press a surface of water inside the water tank, the water tank supplies the cultivation water that has been pressed by the air to a culture medium material arranged inside the cultivation tank from above through the watering channel, the heat-collecting part causes the surface of water inside the water tank to be raised as a result of the heated air being cooled by a decrease of the sunlight, and the water tank suctions the cultivation water from a bottom section of the cultivation tank via the water-sucking pipe in accordance with rising of the cultivation water; characterized in that the cultivation water circulates between the cultivation tank and the pump system; the solar heat pump system comprises a discharge check valve that prevents backflow of the cultivation water supplied from the water tank to the cultivation tank; and a suction check valve that prevents backflow of the cultivation water suctioned from the cultivation tank to the water tank.