PURPOSE: To facilitate arrangements by connecting an upper leader to a lower leader so as to be capable of being folded backward, and by providing both a lock device by which respective leaders are connected so as to be unable to be folded, and a hydraulic cylinder for regulating the tension of a chain.

CONSTITUTION: When a pile driver is transported, a lock pin 24 is drawn out, and a hydraulic cylinder 2 for turning a front bracket 3 is extended to tilt the entire leader 12A backward, and the center of gravity of an upper leader 12b is positioned at the rear of a pivotal pin 20. Then, a hydraulic cylinder 26 for regulating the tension of a chain is gradually extended to slacken the chain 14, and the leader 12b is turned counterclockwise by gravity making the center of the pin 20 so as to be folded, and it is folded in a horizontal position. Thereafter, the bracket 3 is turned clockwise to lower the height of the leader 12A, so that the position for transportation can be obtained. Thus, arrangements at the time when transportation and operation are started can be facilitated.