PROBLEM TO BE SOLVED: To provide an automatic irrigating apparatus for plant culture capable of always supplying a constant amount of water to a plant from the bottom of a culture bed by dissolving the problem of the conventional technology, that is, water is oversupplied with time since the characteristic property of a culture medium is neglected. SOLUTION: An air-introducing device for adjusting water level, which comprises an air introduction part 7 and an air diffusion part 8, is placed in the culture medium. The wetting of the culture medium and the rising of the water level caused by water characteristics are suppressed by the combined action of the air-introducing device and a float-type water valve installed in the irrigating apparatus.
