A fibrous structure, consisting of: long fibers composed of an inorganic material and obtained by dry-spinning followed by baking to crystallize; and short fibers (2, 5) composed of the inorganic material and shorter than the long fibers and obtained by dry-spinning followed by baking to crystallize, the fibrous structure having a three-dimensional net-like structure obtained by mixing the long fibers and the short fibers (2, 5), wherein at least one of the long fibers and the short fibers (2, 5) includes catalyst components capable of promoting particulate matter reduction performance, and wherein the catalyst components are embedded in the long fibers and/or the short fibers (2, 5) themselves, and a part of each catalyst component is covered with the inorganic material composing the long fibers and/or the short fibers (2, 5), wherein a fiber length of the long fibers is between 2 to 10 mm, wherein a fiber diameter of the long fibers is 7 to 15 μm, wherein a fiber length of the short fibers (2, 5) is between 0.1 to 2 mm, wherein a fiber diameter of the short fibers (2, 5) is 3 to 5 μm, wherein the long fibers and the short fibers (2, 5) are included so that a mass ratio of the long fibers and the short fibers (2, 5) is between 2:8 to 5:5, wherein the catalyst components include noble metal, wherein the fiber length represents the largest distance between two points on an outer circumference of a projected profile shape of the fibers, wherein the fiber diameter represents a diameter perpendicular to the fiber length and passing through the middle point of the fiber length and the two points on the projected profile of the fibers, and wherein a density of the fibrous structure is between 0.01 to 0.5 g/cm 3 and a void content of the fibrous structure is 60 vol% or more. long fibers composed of an inorganic material and obtained by dry-spinning followed by baking to crystallize; and short fibers (2, 5) composed of the inorganic material and shorter than the long fibers and obtained by dry-spinning followed by baking to crystallize, the fibrous structure having a three-dimensional net-like structure obtained by mixing the long fibers and the short fibers (2, 5), wherein at least one of the long fibers and the short fibers (2, 5) includes catalyst components capable of promoting particulate matter reduction performance, and wherein the catalyst components are embedded in the long fibers and/or the short fibers (2, 5) themselves, and a part of each catalyst component is covered with the inorganic material composing the long fibers and/or the short fibers (2, 5), wherein a fiber length of the long fibers is between 2 to 10 mm, wherein a fiber diameter of the long fibers is 7 to 15 μm, wherein a fiber length of the short fibers (2, 5) is between 0.1 to 2 mm, wherein a fiber diameter of the short fibers (2, 5) is 3 to 5 μm, wherein the long fibers and the short fibers (2, 5) are included so that a mass ratio of the long fibers and the short fibers (2, 5) is between 2:8 to 5:5, wherein the catalyst components include noble metal, wherein the fiber length represents the largest distance between two points on an outer circumference of a projected profile shape of the fibers, wherein the fiber diameter represents a diameter perpendicular to the fiber length and passing through the middle point of the fiber length and the two points on the projected profile of the fibers, and wherein a density of the fibrous structure is between 0.01 to 0.5 g/cm 3 and a void content of the fibrous structure is 60 vol% or more.