PURPOSE: To enable a work to be mounted/demounted during machining with a pallet separated from a moving means.

CONSTITUTION: Each pallet 17 provided with a pin coupling groove at its side surface, is placed over a plural number of rollers 11, a screw threaded bar 25 is set in the direction perpendicularly intersected with the axial direction of each free roller 11, a carriage 22 threadedly engaged with the threaded bar 25 is set in such a way as to be capable of being moved horizontally, and a pallet carriage device is so constituted that a locate coming and going means 23 allowing a locate pin 24 which is to be coupled in the pin coupling groove, to go in and out is fixed on the carriage 22. In the pallet carrying device, each pallet 17 is placed at both the ends of the free rollers 11 in which the carriage 22 is selectively connected to both the pallets 17. Furthermore, each connecting pallet is so constituted as to be used for the pallet carrying device in which a plural number of pallets 17 to be placed over the free rollers 17, are connected to each other.