To securely fix, by a simple means, the set length of a rod body formed by slidably inserting, into an outer rod, an inner rod having discontinuous projection rows on its outer surface in the longitudinal direction.

The inner rod 3 is slidably inserted into the outer rod 2, and the length of the rod body 5 is set by sliding the inner rod a prescribed distance with a fixing device 6. The discontinuous projection rows 13 comprising projections 12 formed in a discontinuous state in the longitudinal direction are formed on the outer surface of the inner rod 3. The fixing device 6 comprises an inner cylindrical body 22 and an outer cylindrical body 23 threadedly connectable to each other. The inner cylindrical body 22 is fixed to the end part of the outer rod 2, and comprises, in the inner surface thereof, a passing groove 35 for passing the discontinuous projection rows 13 therethrough. A holding piece 45 is installed at the tip portion of the inner cylindrical body between adjacent slits 43 and 44. As the outer cylindrical body 23 is tightened, the holding piece 45 is elastically deformed, and its tip engagement part 63 is brought into contact with the outer surface 11 of the inner rod 3 between the adjacent projections 12 and 12 to receive the end parts 66 of the projections 12 by the tip engagement part 63.