A holding sealing material includes mats which have a longitudinal direction and first and second longer side faces along the longitudinal direction and which include a lower mat and an upper mat laminated on the lower mat. A length of the lower mat in the longitudinal direction is longer than a length of the upper mat in the longitudinal direction. Each of the mats is connected to each other at a fixed portion which extends substantially along a width direction perpendicular to the longitudinal direction. The fixed portion has first and second end portions in the width direction. The first end portion is on a side of the first longer side face. The second end portion is on a side of the second longer side face. The first and second end portions are spaced apart from the first and second longer side face, respectively.