A masking method for honeycomb formed body, including bonding a film on at least one bottom face of a honeycomb formed body in a quadrangular prism shape such that an adhesive surface is in contact with the bottom face. The step of bonding the film includes bonding of the film so as to have a bottom face covering portion that covers a whole surface of the bottom face and a pair of outer edge portions along one pair of opposite sides of a quadrangle defining an outer peripheral shape of the bottom face and a pair of protruding portions protruding from another pair of opposite sides of the quadrangle. At least a part of the adhesive surface of each of the pair of protruding portions is bonded so as to be in contact with a pair of opposing lateral faces of the honeycomb formed body.