PURPOSE: To enable to raise up or bring down a tower satisfactorily, by means of setting up a A-type tower at the both front sides of a pile-driving tower, and of taking up or winding back by a winch by stretchig a wirerope between the seive of the top and the seive of the rear part of the tower corresponding to the seive of the top.

CONSTITUTION: A wire rope 5a is stretched between a seive 5 for raising up or bringing down which was mounted on the top of two A-type towers 4 set up at the front both sides of a pile-driving tower 2 on a bed ship 1 and another seive 5 for raising up or bringing down which was mounted at an optional position of the rear part of the tower, and a fixing pin 3a of an oil pressure cylinder 3 for raising up or bringing down, is taken away from a fixed state of the tower. Next, after to tower being made into a state capable of bringing down the tower over the normal use range angle θ by the oil pressure cylinder, the tower is brought down up to a tower stopper 7 backward by means of taking up the wirerope 5a by the winch 6 on the deck. On the contrary, when the tower is raised up, the wirerope 5a is wound back, thereby the oil pressure cylinder 3 is fixed at the bed ship 1 by the fixing pin 3a.