A sealing device that comprises a gasket portion (10; 10X; 10a) made of an elastic body for sealing a space between an end surface of one of two pipes configuring an intake pipe and an end surface of the other one of the two pipes, and an intake noise reduction portion (20, 20X, 20Y, 20Z, 20ZZ) for reducing intake noise, wherein the intake noise reduction portion (20, 20X, 20Y, 20Z, 20ZZ) comprises: a main body portion for reducing intake noise; an annular frame body portion (22, 22X, 22Y, 22Z) for supporting the main body portion; and a tubular portion (23, 23a; 13X) that extends from the frame body portion (22, 22X, 22Y, 22Z) in a direction in which the pipes extend, and is fitted into an inner circumferential surface of either one of the one pipe and the other pipe; characterized in that the intake noise reduction portion (20, 20X, 20Y, 20Z, 20ZZ) further comprises a flange portion that extends from an end portion of the tubular portion (23, 23a; 13X) toward an outer circumferential surface side, and is disposed in the space between the end surfaces of the one pipe and the other pipe, the gasket portion (10; 10X; 10a) is provided on both surfaces of the flange portion, the main body portion is configured from a flow-guiding net portion (21, 21a, 21X, 21Xa, 21Z, 21ZZ) for guiding a gas flowing in the intake pipe, the flow-guiding net portion (21, 21a, 21X, 21Xa, 21Z, 21ZZ) is configured such that a mesh thereof is fine in a vicinity of a center of a flow passage in the intake pipe and becomes coarser with distance from the vicinity of the center such that more air flows through the region within the intake pipe that is more distant from the vicinity of the center, and the mesh of the flow-guiding net portion (21, 21a, 21X, 21Xa, 21Z, 21ZZ) is formed of a plurality of radial portions extending radially outward from the vicinity of the center of the flow passage in the intake pipe and a plurality of concentric circular portions provided concentrically from the vicinity of the center. a main body portion for reducing intake noise; an annular frame body portion (22, 22X, 22Y, 22Z) for supporting the main body portion; and a tubular portion (23, 23a; 13X) that extends from the frame body portion (22, 22X, 22Y, 22Z) in a direction in which the pipes extend, and is fitted into an inner circumferential surface of either one of the one pipe and the other pipe; characterized in that the intake noise reduction portion (20, 20X, 20Y, 20Z, 20ZZ) further comprises a flange portion that extends from an end portion of the tubular portion (23, 23a; 13X) toward an outer circumferential surface side, and is disposed in the space between the end surfaces of the one pipe and the other pipe, the gasket portion (10; 10X; 10a) is provided on both surfaces of the flange portion, the main body portion is configured from a flow-guiding net portion (21, 21a, 21X, 21Xa, 21Z, 21ZZ) for guiding a gas flowing in the intake pipe, the flow-guiding net portion (21, 21a, 21X, 21Xa, 21Z, 21ZZ) is configured such that a mesh thereof is fine in a vicinity of a center of a flow passage in the intake pipe and becomes coarser with distance from the vicinity of the center such that more air flows through the region within the intake pipe that is more distant from the vicinity of the center, and the mesh of the flow-guiding net portion (21, 21a, 21X, 21Xa, 21Z, 21ZZ) is formed of a plurality of radial portions extending radially outward from the vicinity of the center of the flow passage in the intake pipe and a plurality of concentric circular portions provided concentrically from the vicinity of the center.