A subject of the present invention is to provide an anti AQP3 antibody specifically recognizing the extracellular domain of aquaporin 3 (AQP3), which is one type of a water channel protein. By selecting a monoclonal antibody which specifically binds to an oligopeptide included in loop C as one of the extracellular domains of AQP3, an anti AQP3 antibody that is desired in the present invention is provided. An anti AQP3 monoclonal antibody of the present invention can directly bind, from the outside of a cell, to AQP3 present in a cell membrane. Furthermore, as an anti AQP3 monoclonal antibody of the present invention can have an inhibitory activity, the function of permeating a low molecular weight molecule or the like, which is carried by AQP3, can be suppressed.