To provide a device capable of easily vertically moving a catch fork of a leader used during steel pipe pile driving in foundation work by an operation of one operator from an operator cab.

Attachment of the catch fork used in work is improved from a fixed type to a sliding type and the catch fork is vertically moved by using oil pressure of a crane. Height of the catch fork is held by a hydraulic valve (a check valve). The height of the catch fork can be easily changed even in accordance with work conditions of a job site.