It is an object of the present invention to provide an antibody that binds to a human PGE 2 receptor subtype EP4 and inhibits the function of EP4, or a functional fragment thereof. It is another object of the present invention to provide a medicament comprising the aforementioned antibody or a functional fragment thereof. Mice were immunized with the human PGE 2 receptor subtype EP4, and a monoclonal antibody that suppresses the intracellular cAMP level increase induced by EP4 was screened. In addition, the CDR sequences of the obtained monoclonal antibody were determined.
