PURPOSE: To provide a workbench device for fitting a support for removing a workbench for fitting a support easily and also capable of performing a high lift work efficiently.

CONSTITUTION: A fixed workbench 4 is fit on an end of a boom 5 and a workbench for fitting a support 3 on which a workbench fitting member for fitting the support 2 is adapted to be inserted and mounted in this fixed workbench 4 and this workbench fitting member for fitting the support 2 is adapted to be removable to the support. Thereby, a fine adjustment of boom operation is not required and removing work of the workbench for fitting the support 3 is performed rapidly as the boom operation can be performed by using the workbenches 3, 4 as a guide when removing the workbench for fitting the support 3 to the support D. Work on the other high left can be performed by boarding the other worker on the fixed workbench 4 fit on the end of the boom.