An object of the present invention is to provide a manufacturing method of a honeycomb structural body which makes the profile of a cross section perpendicular to the length direction thereof less likely to generate dispersion, and also makes the thickness of its sealing material layer thinner, and a sealing material that is suitably used in the manufacturing method of the honeycomb structural body. According to the present invention, the manufacturing method of a honeycomb structural body with a sealing material layer formed on the peripheral portion of a pillar-shaped porous honeycomb member includes a sealing material applying step of applying a paste-like sealing material, which is a raw material of the sealing material layer, onto a circumferential face of the pillar-shaped porous honeycomb member, and a scraping step of fitting a ring-shaped scraper, which can be brought into contact with the circumferential face of the pillar-shaped porous honeycomb member so as to slide thereon, to the pillar-shaped porous honeycomb member and moving said ring-shaped scraper in the length direction, thereby expanding the paste-like sealing material applied onto the circumferential face of the pillar-shaped porous honeycomb member so as to spread over the entire circumferential face of the pillar-shaped porous honeycomb member.