A honeycomb structure includes a pillar-shaped honeycomb structure body having a porous partition wall disposed to surround a plurality of cells, wherein a major component of the partition wall is cordierite, a porosity of the partition wall is 45 to 55%, an average pore diameter of the partition wall is 8 to 19 μm, a cumulative pore volume of the partition wall is such that a pore volume ratio of the pores having a pore diameter larger than a thickness of the partition wall relative to an overall pore volume of the partition wall is 3.0% or less, and a pore volume ratio of the pores having a pore diameter of 10 μm or less relative to the overall pore volume of the partition wall is 30% or more, and a pore diameter distribution of the partition wall is a unimodal distribution, or a multimodal distribution.