A honeycomb structured body, comprising: a ceramic block formed by a plurality of honeycomb fired bodies combined with one another with an adhesive layer interposed therebetween, each of said honeycomb fired bodies having a large number of cells placed in parallel with one another in a longitudinal direction with a cell wall therebetween; and a sealing material layer formed on a peripheral face of said ceramic block, wherein said honeycomb fired bodies comprise first-shaped units, second-shaped units, and third-shaped units, each of said first-shaped units has a quadrangular shape in a cross section perpendicular to the longitudinal direction, each of said second-shaped units has a shape that includes at least a first side, a second side longer than said first side and making a right angle with said first side, and an inclined side facing said right angle in the cross section perpendicular to the longitudinal direction, each of said third-shaped units has a right triangular shape with a hypotenuse and adjacent sides in the cross section perpendicular to the longitudinal direction, each of said second-shaped units is disposed in a peripheral portion of said ceramic block in such a manner that said inclined side is in contact with said sealing material layer, each of said third-shaped units is disposed on the inner side of said second-shaped units in said ceramic block in such a manner that the hypotenuse faces said second side of any one of said second-shaped units with said adhesive layer therebetween, said first-shaped units include peripheral first-shaped units, each of said peripheral first-shaped units is disposed in such a manner as to have two sides, one side facing one of the adjacent sides of one third-shaped unit with said adhesive layer therebetween, the other side facing one of the adjacent sides of another third-shaped unit with the adhesive layer therebetween, said two sides of each of said peripheral first-shaped units or extensions thereof are each neither parallel nor perpendicular to an extension of said second side and an extension of said first side of each of said second-shaped units, said peripheral first-shaped units include outermost first-shaped units that are disposed in the peripheral portion of said ceramic block, each of said outermost first-shaped units has a side that is in contact with said sealing material layer, and said sealing material layer has a larger thickness in a portion that is in contact with each of said outermost first-shaped units than in a portion that is in contact with said inclined side of each of said second-shaped units. a ceramic block formed by a plurality of honeycomb fired bodies combined with one another with an adhesive layer interposed therebetween, each of said honeycomb fired bodies having a large number of cells placed in parallel with one another in a longitudinal direction with a cell wall therebetween; and a sealing material layer formed on a peripheral face of said ceramic block, wherein said honeycomb fired bodies comprise first-shaped units, second-shaped units, and third-shaped units, each of said first-shaped units has a quadrangular shape in a cross section perpendicular to the longitudinal direction, each of said second-shaped units has a shape that includes at least a first side, a second side longer than said first side and making a right angle with said first side, and an inclined side facing said right angle in the cross section perpendicular to the longitudinal direction, each of said third-shaped units has a right triangular shape with a hypotenuse and adjacent sides in the cross section perpendicular to the longitudinal direction, each of said second-shaped units is disposed in a peripheral portion of said ceramic block in such a manner that said inclined side is in contact with said sealing material layer, each of said third-shaped units is disposed on the inner side of said second-shaped units in said ceramic block in such a manner that the hypotenuse faces said second side of any one of said second-shaped units with said adhesive layer therebetween, said first-shaped units include peripheral first-shaped units, each of said peripheral first-shaped units is disposed in such a manner as to have two sides, one side facing one of the adjacent sides of one third-shaped unit with said adhesive layer therebetween, the other side facing one of the adjacent sides of another third-shaped unit with the adhesive layer therebetween, said two sides of each of said peripheral first-shaped units or extensions thereof are each neither parallel nor perpendicular to an extension of said second side and an extension of said first side of each of said second-shaped units, said peripheral first-shaped units include outermost first-shaped units that are disposed in the peripheral portion of said ceramic block, each of said outermost first-shaped units has a side that is in contact with said sealing material layer, and said sealing material layer has a larger thickness in a portion that is in contact with each of said outermost first-shaped units than in a portion that is in contact with said inclined side of each of said second-shaped units.