A honeycomb structural body and a method of manufacturing the honeycomb structural body, the honeycomb structural body comprising a honeycomb structure part having partition walls (2) forming a plurality of cells (3) partitioned in honeycomb shapes and forming recessed parts (6) in the outer peripheral surfaces thereof and an outer wall part (5) disposed on the outer peripheral surface of the honeycomb structure part. In the honeycomb structural body, spaces are formed in the recessed parts (6) between the outer wall part (5) and the honeycomb structure part. By the honeycomb structural body and the method of manufacturing the honeycomb structural body, the lowering of temperature rising rate can be suppressed while suppressing the lowering of a mechanical strength, and the occurrence of cracks can also be suppressed.