Clamp jig and method of polishing workpiece

A method of polishing a workpiece in which a clamp jig is used and a lower end of the clamp jig is polished by a rotary surface plate, the clamp jig including:

• a workpiece bonding member in which a curved workpiece is bonded to one end side thereof to be held;
• one clamping member and the other clamping member between which an end of the workpiece bonded to the workpiece bonding member to be held is sandwiched from both sides thereof;
• an elastic member made of an elastic material that comes in contact with an end of the one clamping member;
• and a plurality of holding members that push the workpiece by supporting the end of the workpiece at multiple points of the elastic member, wherein
• when the surface plate rotates, the clamp jig reciprocally moves in a radial direction of the surface plate in a state where the end of the workpiece is maintained between the one and the other clamping members while being curved by the elastic member and the plurality of holding members.