An optical disk drive capable of detecting occurrence of tooth jump in a mechanism for transferring an optical pickup. A position-indicative signal characterized by a fundamental frequency F is received from a data path including the transducer head. The control procedure then updates the torque upper limit Tmax by a slope of a small time change to restrain the degree of cancellation of the torque restriction. The assembly is delivered to the graft using the holder and the sutures can be affixed to the graft without penetrating therethrough.