A method of manufacturing a honeycomb structured body, includes providing an application jig. A sealing material paste is put on a peripheral surface of a pillar-shaped ceramic block. The application jig is set in such a manner that a first principal surface of the application jig faces upward and a second principal surface of the application jig faces downward. The ceramic block is placed inside a second opening section of the application jig. The ceramic block is passed through an opening section of the application jig so that a face defining the second opening section spreads an entire peripheral surface of the ceramic block with the sealing material paste to manufacture a honeycomb structured body with a peripheral sealing material layer formed on the peripheral surface of the ceramic block.