<p>A slider 37 having a rod-pressing portion 35 for pressing a rod 23 into a rod-engaging recess 25 is movably provided on a holder body 27 having the rod-engaging recess 25. The holder body 27 includes a pressing state holding mechanism for relatively moving the slider 37 with respect to the holder body 27 to hold the rod 23 in a state in which the rod 23 is pressed against the rod-engaging recess 25 by the rod-pressing portion 35. The pressing state holding mechanism includes a screw rod movably, detachably and threadedly engaged with a screw hole formed in the holder body 27. A tip end of the screw rod 45 and the slider 37 connected to each other such that they permit rotation of the screw rod 45 with respect to the slider 37 but move integrally with respect to the holder body 27, and the slider 37 can be attached to and detached from the slider 37. <IMAGE> <IMAGE></p>
