Clamping apparatus

A clamping apparatus having a workpiece cradle reciprocable between a clamp position and a retreat position and a clamp arm for fastening workpieces along with the workpiece cradle, the clamping apparatus comprising:

• a moving block to which said workpiece cradle is attached and an arm opening/closing cylinder for opening and closing said clamp arm is attached;
• a manifold block arranged so as to face said moving block via a guide block and provided with a workpiece-cradle driving supply/discharge port and an arm driving supply/discharge port;
• a workpiece-cradle driving cylinder that is attached between said guide block and said manifold block and in which a moving piston having a piston rod fixed to said moving block is assembled and a fluid chamber communicating with said workpiece-cradle driving supply/discharge port is formed;
• a guide rod that is fixed to said moving block and in which a hollow hole communicating with a fluid chamber of said arm opening/closing cylinder and communicating with a fluid supply/discharge path formed in said moving block is formed;
• and
• a guide cylinder attached between said guide block and said manifold block, guiding said guide rod movably, and communicating with said arm driving supply/discharge port,
• wherein fluid is supplied to said arm opening/closing cylinder via said fluid supply/discharge path and said hollow hole.