A photocatalytic device comprising: a photocatalytic filter having a surface on which a photocatalyst is carried, the photocatalytic filter being formed of a corrugated member having a plurality of ridges and a plurality of valleys alternately arranged, the photocatalytic filter having light-passing holes that allow ultraviolet light or visible light to pass therethrough, at top portions of the ridges and bottom portions of the valleys ; a light irradiation unit configured to irradiate one of front and rear surfaces of the photocatalytic filter with ultraviolet light or visible light; a reflection wall facing the other one of the front and rear surfaces of the photocatalytic filter , the reflection wall reflecting light that has been emitted from the light irradiation unit and has passed through the light-passing holes of the ridges and the valleys of the photocatalytic filter , toward the other surface; a gas inflow part and a gas outflow part respectively provided at one end and the other end of the photocatalytic filter , the gas inflow part and the gas outflow part allowing a gas to flow in a space between the light irradiation unit and the photocatalytic filter and a space between the reflection wall and the photocatalytic filter , over the front and rear surfaces of the photocatalytic filter from the one end toward the other end along a direction in which the ridges and the valleys extend; and a support member configured to support the photocatalytic filter at the one end or the other end, wherein the support member supports the light irradiation unit ; and characterized in that the support member is metallic and the photocatalytic filter is metallic, the corrugated member being made of a metal material. a photocatalytic filter having a surface on which a photocatalyst is carried, the photocatalytic filter being formed of a corrugated member having a plurality of ridges and a plurality of valleys alternately arranged, the photocatalytic filter having light-passing holes that allow ultraviolet light or visible light to pass therethrough, at top portions of the ridges and bottom portions of the valleys ; a light irradiation unit configured to irradiate one of front and rear surfaces of the photocatalytic filter with ultraviolet light or visible light; a reflection wall facing the other one of the front and rear surfaces of the photocatalytic filter , the reflection wall reflecting light that has been emitted from the light irradiation unit and has passed through the light-passing holes of the ridges and the valleys of the photocatalytic filter , toward the other surface; a gas inflow part and a gas outflow part respectively provided at one end and the other end of the photocatalytic filter , the gas inflow part and the gas outflow part allowing a gas to flow in a space between the light irradiation unit and the photocatalytic filter and a space between the reflection wall and the photocatalytic filter , over the front and rear surfaces of the photocatalytic filter from the one end toward the other end along a direction in which the ridges and the valleys extend; and a support member configured to support the photocatalytic filter at the one end or the other end, wherein the support member supports the light irradiation unit ; and characterized in that the support member is metallic and the photocatalytic filter is metallic, the corrugated member being made of a metal material. <EOS>