A honeycomb structure includes four honeycomb units each including inorganic particles, an inorganic binder, and cell walls extending from a first end face to a second end face along a longitudinal direction to define a plurality of cells. The cell walls includes a first cell walls extending along a first direction in a cross sectional plane perpendicular to the longitudinal direction and a second cell walls extending along a second direction substantially perpendicular to the first direction in the cross sectional plane. Adhesive layers are provided between the four honeycomb units to connect the four honeycomb units. The adhesive layers extend in a first extending direction and a second extending direction substantially perpendicular to the first extending direction in the cross sectional plane. A minimum angle between the first direction and the first extending direction or the second extending direction is approximately 22.5 degrees to approximately 45 degrees.