To obtain a ceramic honeycomb structure capable of further improving an isostatic fracture strength and a thermal shock resistance even at a thin cell wall of 0.15 mm or less without necessity of a separate step in the case of molding.

The ceramic honeycomb structure comprises an outer peripheral wall and a plurality of cell walls in the peripheral wall. In this structure, a radius (Rr) of an intersection of the peripheral wall with the cell wall is larger than a radius (Rc) of an intersection of the cell walls with each other. Here, it is preferred that the radius (Rr) of the intersection of the peripheral wall with the cell wall and the radius (Rc) of the cell walls satisfy Rr/Rc=1.2 to 2 and Rc is 0.25 mm or less.