A honeycomb structure, comprising: a columnar honeycomb structure body (4, 34, 54) that has a partition wall (1, 31, 51), the partition wall defining a plurality of cells (2, 32, 52), the cells extending from a first end face (11, 41, 61) to a second end face (12, 42, 62) and becoming channels for fluid, wherein the partition wall (1, 31, 51) is constituted of a porous body, the porous body including a refractory aggregate and a bonding material, the bonding material having a main constituent of an oxide material, the bonding material bonding the refractory aggregates, the porous body constituting the partition wall includes the bonding material at a mass proportion of 20 to 35 mass % and includes an alkaline earth metal oxide sintering aid, and in an observation of a cross section of the partition wall (1, 31, 51) perpendicular to the cell extending direction of the honeycomb structure body with an electron microscope, when observing any given ten visual fields meeting the following condition, the number of refractory aggregates meeting the following condition is five pieces or more in all of the ten visual fields: condition: the visual field is 100 μm square, and in the visual field, a proportion of an area occupied by the bonding material to a total area of the refractory aggregate and the bonding material in the visual field is 30% or more, condition: the refractory aggregate has a particle diameter of 5 μm or more, and 60% or more of an outer circumference of the refractory aggregate is surrounded by the bonding material, and wherein the bonding material has a main constituent of: an oxide of at least one metal selected from Al, Si and Mg; or a mixture of oxides each of at least one metal selected from Al, Si and Mg. a columnar honeycomb structure body (4, 34, 54) that has a partition wall (1, 31, 51), the partition wall defining a plurality of cells (2, 32, 52), the cells extending from a first end face (11, 41, 61) to a second end face (12, 42, 62) and becoming channels for fluid, wherein the partition wall (1, 31, 51) is constituted of a porous body, the porous body including a refractory aggregate and a bonding material, the bonding material having a main constituent of an oxide material, the bonding material bonding the refractory aggregates, the porous body constituting the partition wall includes the bonding material at a mass proportion of 20 to 35 mass % and includes an alkaline earth metal oxide sintering aid, and in an observation of a cross section of the partition wall (1, 31, 51) perpendicular to the cell extending direction of the honeycomb structure body with an electron microscope, when observing any given ten visual fields meeting the following condition, the number of refractory aggregates meeting the following condition is five pieces or more in all of the ten visual fields: condition: the visual field is 100 μm square, and in the visual field, a proportion of an area occupied by the bonding material to a total area of the refractory aggregate and the bonding material in the visual field is 30% or more, condition: the refractory aggregate has a particle diameter of 5 μm or more, and 60% or more of an outer circumference of the refractory aggregate is surrounded by the bonding material, and wherein the bonding material has a main constituent of: an oxide of at least one metal selected from Al, Si and Mg; or a mixture of oxides each of at least one metal selected from Al, Si and Mg. condition: the visual field is 100 μm square, and in the visual field, a proportion of an area occupied by the bonding material to a total area of the refractory aggregate and the bonding material in the visual field is 30% or more, condition: the refractory aggregate has a particle diameter of 5 μm or more, and 60% or more of an outer circumference of the refractory aggregate is surrounded by the bonding material, and wherein the bonding material has a main constituent of: an oxide of at least one metal selected from Al, Si and Mg; or a mixture of oxides each of at least one metal selected from Al, Si and Mg.