To provide a mouthpiece of a vice capable of advancing and retracting in accordance with inclination and recessed and projecting parts of a workpiece and gripping the workpiece stably, preventing local deformation of the workpiece, having a simple structure, and being suitable for a compact vice.

The workpiece is gripped by a plurality of plungers 3. This mouthpiece is provided with the plunger 3 inserted into a plunger hole 5 provided in a mouthpiece body 2 so as to move in play in the axial direction, a connection hole 9 connecting bottom parts of the plunger holes 5, and a plurality of transmission members 11, 17 inserted into the connection hole 9 so as to move freely in the longitudinal direction. The transmission member in the bottom part of the plunger hole 5 among the transmission members 11, 17 is a roller 11 or a ball 17, and an inclined face 15 or a circular arc face 10 converting the direction of travel of the travel of the plunger 3 in the axial direction and the travel of the transmission members 11, 17 in the longitudinal direction through the roller 11 or the ball 17 is provided.