To provide an automatic PET bottle waterer system using a PET bottle as the water reservoir, applicable to all kinds of and all sizes of plants and capable of easily supplying water with stepless supply amount, wherein the all size of the PET bottles can be used and the waterer can be applied to water supply, liquid manure replenishment and herbicide application.

This system is obtained by attaching a PET bottle water reservoir (A) to a PET bottle automatic waterer (B) and also attaching to a PET bottle reservoir fixing stand (D), wherein a water supply hole (6) is set on the automatic PET bottle waterer (B) and a nozzle (5) of automatic PET bottle waterer is inserted into a horticultural soil (C) to supply water. By adjusting opening of an air suction adjusting cock (3) of an air control valve (2), air suction is adjusted to control air suction amount, thereby, to easily perform stepless control of the water and to supply necessary water regardless of plant kind and size. The PET bottle regardless of size and shape can be applied to the PET bottle water reservoir (A).