PURPOSE: To perform a job for pile driving so efficiently as well as to make this pile driving achievable even in the case where there is an obstable or the like.

CONSTITUTION: A front attachment 23, whose tip is vertically liftable and its horizontal reachable position is alterable, is attached to a mobile working machine 20. This attachment 23 is attached so as to make a horizontal sense of the tip be alterable by a turning gear 24 of a working machine body 21 or another turning gear to turn the whole body or part of the attachment. Each lifting guide 43 is symmetrically hung down from the tip of the front attachment 23. Then, a ram lifting pile driver 21 is installed between these symmetrical lifting guides 43 free of lifting motion along these guides 43. In this case, a connecting pin 48 of the lifting guides 43 to the front attachment 23 is structured that it is prevented from being projected out of an upper end of the pile driver 21.