A holding sealing material includes inorganic fibers, a mat shape, a first and a second end faces, a contact section and a void-forming section. The first end face and the second end face are approximately parallel in a width direction. The contact section includes a first distance between the first and the second end faces. The first distance is longest in a length direction. The void-forming section includes a second distance between the first and the second end faces. The second distance is shorter than the first distance. The holding sealing material has a structure to provide a void in a vicinity of the first and the second end faces of the void-forming section in a state where the holding sealing material is rolled up so that the first end face is made in contact with the second end face of the contact section.