In recent years, autonomous unmanned underwater vehicles (AUVs) for underwater exploration are studied and developed activity. It is important to control the position and attitude of an AUV in underwater with stream change. A conventional AUV moves underwater using screw propellers. In underwater, fishes control own fins and body more freely than an AUV using screw propellers. A kind of the neural oscillator that generates periodic movement of living thing is called a central pattern generator (CPG). In this paper, we develop an underwater exploration robot that mimics a Manta out of many fishes, where its mechanical reproduction is easy relatively. Furthermore, a CPG is proposed to control the propulsive power by the pectoral fins of the Manta robot. The effectiveness of the proposed method is verified by the experiment using the developed Manta robot.