The object is to isolate and identify human and mouse adiponectin receptors, to provide a novel protein having adiponectin binding ability, and to provide a screening method and screening kit for a ligand, agonist and antagonist to an adiponectin receptor using such protein. To achieve this object, a protein is used, as novel protein having adiponectin binding ability, that is (a) a protein comprising an amino acid sequence according to Seq. No. 2, 4, 6 or 8, or (b) a protein comprising an amino acid sequence according to Seq. No. 2, 4, 6 or 8 with one or more amino acids deleted, replaced or added, and having adiponectin binding ability.
