An artificial soil aggregate which is an aggregate of artificial soil particles is provided. When an artificial soil is formed by filling a container, such as a planter, etc., with the artificial soil aggregates, the volumetric moisture content rate and gas phase fraction of the artificial soil can be improved, and can also be maintained over a long period of time. The artificial soil aggregate is an aggregate of artificial soil particles in which a plurality of fillers having a small hole ranging from the subnanometer to the submicrometer scale are clustered together. A communication hole ranging from the submicrometer to the submillimeter scale is formed between the fillers. The artificial soil aggregate has a volumetric moisture content rate of 10 to 40% at a pF ranging from 1.7 to 2.3, and a gas phase fraction of 20 to 80% at a pF of 1.5.