A novel hemopoietin receptor gene (NR12) was successfully isolated by extracting motifs conserved among the amino acid sequences of known hemopoietin receptors and by using the predicted sequence. The NR12 gene encodes two forms of proteins, a transmembrane type and a soluble type. The expression of the NR12 gene was detected in tissues containing hematopoietic cells. NR12 is a novel hemopoietin receptor molecule involved in the regulation of immune system and hematopoiesis in vivo. Thus, NR12 is useful in the search for novel hematopoietic factors that functionally bind to the NR12 receptor, and in the development of therapeutic drugs for diseases associated with immunity or hematopoiesis.