To provide a device suppressing the leakage of fluid slurry remaining in a workpiece holder when taking out the workpiece after machining, and preventing the fluid slurry remaining in the workpiece holder from becoming an obstacle to filling the next workpiece.

A ferrule holder body 27 included in a first workpiece holder 11 of a pair of workpiece holders is pressed against and tightly contacted with a ferrule holder body 26 included in a second ferrule holder 6 of the pair, thereby sealing a flow path line. Fluid passages 45, 48 communicating to a vertical direction pipe 13 are provided on at least the workpiece holder 11 of the workpiece holders 11, 6 fixed on a fixing block 4. Air or an aqueous solvent is led in the flow passages 45, 48 through check valves 46, 49.