To provide a fastening chuck for machine tool capable of easily checking whether a clamp jaw is sufficiently deeply put into a radial direction guide groove 4 in the fastening chuck for machine tool provided with a chuck body 3 connected with a chuck flange 2, several clamp jaws 5 arranged in the radial direction guide groove 4 of the chuck body 3 and a wedge rod 7 movable by crossing the guide groove 4 in a wedge rod pocket 6 in the chuck body 3 so as to drive the clamp jaw 5 and provided with a helical gear type gear train 8 engaged with a corresponding tooth space 9 of the clamp jaw 5.

In the wedge rod 7, a check bolt 10 and a locking bolt 11 are mounted so as to movable in an axial direction of the chuck body 3, and a connecting member 12 for simultaneously moving the bolts 10, 11 in opposite directions and a spring for moving the check bolt 10 to the side of the guide groove 4 are arranged. In the chuck flange 2, a locking accepting part 14 for accepting the locking bolt 11 when the check bolt 10 is engaged with the guide groove 4 is provided.