PURPOSE: To make it possible to handle easily and enhance workability and operate safely and efficiently without any need for cutting a hydraulic hole by clamping an object article substantially in the center of two work arms.

CONSTITUTION: In a work device where a pair of work arms (1) and (2) driven by an hydraulic cylinder (9) are rotatively supported on side plates (6) and (7) of a frame by means of a pin 15, a stopper (4) which regulates the opening positions of the work arms (1) and (2) and a stopper which regulates a closing position of the work arm, are installed to the paired work arms respectively. The side plates (6) play the part of a stopper receiver in the stopper (4) which regulates the opening position of the work arm. The stopper which regulates the closing position of the work arm is provided with the work arm having a stopper receiving part.