PURPOSE: To fix a work by setting it in a specific erecting position surely within a plane orthogonal with the front and back moving direction of a movable jaw, by combining a square columnar holder main body, clamp block and clamp screw.

CONSTITUTION: In case of fitting a holder main body 11 to the front face of the fixed jaw V1 of a vice V, a clamp block 12 is arranged in vertical direction at one end side of the front face of the holder main body 11 between the holder main body 11 and a movable jaw V2. So, a work W is held by hand so as to abut one face to the clamp block 12 and a clamp screw 13 is advanced, and then the work W is provisionally stopped in the specific erecting position regulated by the clamp block 12. Thereafter, the work W is interposed in the space with the fixed jaw V1 via the holder main body 11, by advancing the movable jaw V2. Consequently, the work W can be set by fixing in the specified erecting position simply.