PROBLEM TO BE SOLVED: To provide an apparatus for achieving the modification of a liquid by particles and a plate containing photocatalytic titanium oxide and the others as one of apparatuses for eliminating a substance harmful to a thing in a living space and to achieve the reduction of wastewater treatment cost by allowing good wastewater to flow by a water-using person. SOLUTION: In this liquid modifying apparatus, a liquid brought into close contact with photocatalytic titanium oxide particles or the like is irradiated with solar rays, ultraviolet rays due to a light and aphotic particles due to electrons to be modified. The apparatus is changed by purpose or use. COPYRIGHT: (C)2003,JPO