Abstract: Photocatalyst particle bodies filled in optically transparent containers, which can fulfill the photocatalytic function without losing the function of the photocatalyst particles not only on the surface side but also on the inner side even when the insides of the containers are provided with a treatment structure that treated water passes through and are easily recovered and recycled are provided wherein photocatalyst fine particles of apatite-coated titanium dioxide or the like are contained in hollow shells made of a thermoplastic resin such as polystyrene having optical transparency, air permeability, and water permeability obtained by a drying in liquid method, and a particle body size thereof is not less than 1 millimeter.