A honeycomb structure includes honeycomb units. Each of the honeycomb units has a longitudinal direction and includes inorganic particles, an inorganic binder, and cell walls defining cells extending along the longitudinal direction from one end face to another end face. The honeycomb units are bonded together via an adhesive such that each longitudinal direction is substantially in parallel. An amount of ammonia desorbed per unit mass of the honeycomb units is about 5 to about 100 times greater than an amount of ammonia desorbed per unit mass of the adhesive. The amount of ammonia desorbed per unit mass of the honeycomb units and the amount of ammonia desorbed per unit mass of the adhesive are measured by an NH3-TPD method.