The present invention aims to provide a novel gene having a reverse transcriptase motif. The invention isolates a novel gene having a reverse transcriptase motif, and gives its complete base sequence determined. The invention also provides a protein encoded by the gene, and an antibody against the protein. The use of them is useful in developing a method for detecting telomerase activity, a method for detecting a cancer cell, a telomerase activity inhibitor, and a method for screening a telomerase activity inhibitor.