The present invention relates to an automatic moisture supply device of a plant cultivator using residual moisture of stratum, which is inserted into and fixed to stratum of the bare ground in a state of not having an artificial water supply source such as a separate water tank, and is to automatically supply moisture for a long time to have a stable growth environment of an edible plant and an ornamental plant planted in a plant cultivator such as a flowerpot accommodated with bed soil, and to maintain growth activities in an optimal condition. The automatic moisture supply device of a plant cultivator of the present invention comprises: a first cylindrical container inserted by a predetermined depth to be fixed to stratum, and erected toward the ground by a predetermined height； a second cylindrical container inserted into an inner diameter of the first cylindrical container at a predetermined interval in a circumferential direction, and having an accommodation space inside a predetermined cylinder； an annular column-shaped moisture transfer space formed between the inner diameter of the first cylindrical container and an outer diameter of the second cylindrical container, and forming a transfer path of collected stratum moisture； a stratum moisture transfer body filled in the moisture transfer space, and combined with phyllite powder and bentonite granules forming surface tension and adhesion by a capillary phenomenon to collect moisture remaining in the stratum and to transfer the same by 1 m or more； and a planting environment providing unit fixed and coupled to an end of the first cylindrical container along an outer diameter thereof, and providing the moisture for a growth environment of an edible plant and ornamental plant planted in accommodated bed soil from the stratum moisture transfer body of the moisture transfer space.본 발명은 별도의 물탱크나 수조와 같은 인위적인 물공급원이 없는 상태에서 노지의 지층에 삽입고정되어 있고, 용토가 수용된 화분같은 식물재배기에 식재된 식용식물 및 관상용 식물의 생육환경이 안정적이며 최적의 생태로 생장활동을 유지하도록 수분을
