A plant cultivation device is provided in which soil (plant cultivation bed material) is unlikely to be in a state with excessive moisture. Specifically, a plant cultivation device and a feed-water control method are provided in which a moisture sensor is easily buried, and a detected moisture amount to start watering and a water amount to be used per watering are easily determined. For this purpose, there are provided: a plant cultivation container (1) for pooling plant cultivation water; a water-absorbing plant cultivation bed material (20A,20B); a feed-water device (30) for supplying the plant cultivation water to the plant cultivation container (1); a first moisture sensor (S1) for detecting moisture around an immersed part (24) of the plant cultivation bed material (20A,20B); a second moisture sensor (S2) for detecting moisture around a growth part (25) of the plant cultivation bed material where a root of a plant is received; and a controller for supplying water when values detected by both of the first and second moisture sensors (S1,S2) are below respective reference values (Rm1,Rm2), and for stopping water supply when a value detected by either the first or second moisture sensor (S1,S2) is above the corresponding reference value.
