To suppress flexural vibration of a beam of a transfer device without raising the flexural rigidity of the beam and without conducting feedback-control by a vibration sensor or the like.

At a stop position C1 of a clamp stroke curve C for laterally moving the beam, a both-beam-end supporting part is additionally reciprocated in the moving direction before stopping for the time of a half period T/2 of flexural vibration of the beam, while synchronizing the reciprocating movement with the flexural vibration, which is generated by inertial force on stopping intermittent movement of the beam. Thereby, the flexural displacement of the central part of the beam is synchronized with the support position of the both ends of the beam, and flexural vibration of the beam of the transfer device is suppressed without raising the flexural rigidity of the beam and without conducting feedback-control by a vibration sensor or the like.