PURPOSE: To provide a vise incorporating a boost mechanism, which can mechanically indicate a fastening force so as to appropriately indicate a clamping condition of a workpiece, and which has a structure which is simple and inexpensive.

CONSTITUTION: A vise 10 comprises a movable jaw 10, a stationary jaw 4, a drive shaft 6 fitted in a frame 2 so as to be movable in a clamping direction, for moving the movable jaw 10, relative to the stationary jaw 4, a boost mechanism 12, a rod 18 inserted in the drive shaft 6 so as to come into and out from the boost mechanism 12, a drive shaft 16 for allowing the rod 18 to come in and out from the boost mechanism 12 when it is rotated, and a nut 20 attached to the drive shaft 16 so as to be unrotatable, and threadedly fitted on the drive shaft 16 so as to be movable in the clamping direction. A holder 30 is integrally incorporated with the drive shaft 6, and a resilient member 34 is interposed between the nut 20 and the holder 30 which are therefore urged to separate from each other. Marks 36 which can indicate variation in the relative position of the holder 30 are provided on the outer surface of the nut 20.