A honeycomb structural body includes at least one honeycomb unit including a β type zeolite, a phosphate group zeolite, and an inorganic binder and having a plurality of through holes divided by partition walls and arranged in a longitudinal direction of the honeycomb unit. The β type zeolite includes secondary particles having an average particle diameter of approximately 0.5 μm or more and approximately 5 μm or less. The phosphate group zeolite includes primary particles having an average particle diameter of approximately 0.5 μm or more and approximately 5 μm or less. A ratio of a mass of the phosphate group zeolite with respect to a total mass of the β type zeolite and the phosphate group zeolite is approximately 5% or more and approximately 35% or less.