A honeycomb structure includes a honeycomb block which includes at least one honeycomb fired body having a first end face side and a second end face side in a longitudinal direction of the honeycomb fired body. The honeycomb fired body includes a plurality of cell walls extending along the longitudinal direction to define cells. Either one of first and second end portions in the longitudinal direction of each of the cells is sealed. The first end portion provided on the first end face side of the at least one honeycomb fired body is sealed with a first plug which is made from a plug material paste and fired. The second end portion provided on the second end face side of the at least one honeycomb fired body is sealed with a second plug which is made from a plug material paste and unfired.