As a visible-light-responsive photocatalytic-titanium-oxide-particulate dispersion liquid that can achieve a high visible light activity and is of a type different from the related art, the present invention provides a visible-light-responsive photocatalytic-titanium-oxide-particulate dispersion liquid in which two types of titanium oxide particulates are dispersed in an aqueous dispersion medium. The two types of titanium oxide particulates are first titanium oxide particulates, in which a tin component and a transition metal component (but excluding an iron-group component) for enhancing visible light responsiveness are dissolved, and second titanium oxide particulates, in which an iron-group component is dissolved. When a photocatalytic film formed by using this dispersion liquid is used, a high decomposition activity is achieved even in a case where a decomposition substrate has low concentration, which was previously difficult under visible light conditions.一種可見光應答型光觸媒氧鈦微粒子分散液，其特徵係於水性分散介質中分散固熔有錫成分及提高可見光應答性之過渡金屬成分(但鐵族成分除外)之第1氧鈦微粒子與固熔有鐵族成分之第2氧鈦微粒子之2種氧鈦微粒子。一種可見光應答型光觸媒氧鈦微粒子分散液，其特徵係於水性分散介質中分散固熔有錫成分及提高可見光應答性之過渡金屬成分之第1氧鈦微粒子與固熔有鐵族成分之第2氧鈦微粒子之2種氧鈦微粒子。
