Abstract: A honeycomb structured body of the present invention is a honeycomb structured body in which plural pillar-shaped honeycomb units are bonded to one another through sealing material layers, each unit having in the longitudinal direction a large number of cells placed in parallel with a cell wall interposed therebetween. Herein, each honeycomb unit includes inorganic fibers and/or whiskers in addition to inorganic particles. A cross-sectional area of the honeycomb unit on a cross section perpendicular to the longitudinal direction is at least about 5 cm2 and at most about 50 cm2. A region in which a sealing material layer is not formed is provided on both ends of the side faces of each of the honeycomb unit, each of the ends accounting for at least about 0.3% and at most about 5% of the length of the honeycomb structured body.