To provide a work vice for preventing an error in machining a work resulting from a clearance or dimensional error of a sliding portion, achieving micron gripping position accuracy and permitting readjustment of the position of a movable jaw or the clearance of the sliding portion.

The work vice comprises a base 1 approximately L-shaped in a side view, a fixed jaw 2, a guide bar 6 and the movable jaw 14. The base 1 has a bottom portion 3 to be fixed to a table of a machine tool and a supporting portion 4 projecting upward from one end thereof, on which the guide bar 6 is mounted at the upper parts or the intermediate parts of both the supporting portion 4 and the fixed jaw 2 at their projection heights for guiding the movable jaw. Both ends of the guide bar 6 are provide with fitting members for restricting the displacement in the direction of isolating the supporting portion 4 and the fixed jaw 2 from each other. A plurality of horizontal adjusting screws are threaded around fixed bolts at both ends of the guide bar 6.