When a polybasic acid salt containing at least one species selected from the group consisting of an alkaline earth metal, a transition metal, and Al is caused to be present on the surfaces of titanium dioxide fine particles, there are obtained photocatalytic particles and powder exhibiting sufficient photocatalytic properties when irradiated with light from a light source of low quantity of light. By use of the photo-functional particles and powder, an organic polymer composition, a slurry, a coating agent, and a product having a surface exhibiting photocatalytic property and hydrophilicity are obtained.