It is intended to allow for efficiently performing a feeder replacement operation. A feeder 50 is formed in a shape elongated in one direction to allow a replacement operation therefor to be performed in such a manner that it is inserted and pulled out relative to a feeder installation section 150, along a longitudinal direction thereof. A rear end 111 which is a trailing one of longitudinally opposite ends of each of a plurality of feeders 50A, 50B, - - - , in an insertion direction, is provided with a guide portion for guiding one 50C of the feeders to be installed in adjacent relation to ones of the remaining feeders. For example, the guide portion can be formed by rounding corners of the rear end 111 of the feeder 50.