Provided is a mobile workbench constructed so as to determine that an accident of some kind has occurred and to stop if the speed of the mobile workbench suddenly changes. A mobile workbench (A) travels on a material (Ca) to be processed and performs predetermined processing (welding) by using a processing tool (welding torch (B)) mounted thereon. The mobile workbench (A) comprises: a workbench main body (1); a plurality of wheels (4) which are provided on the workbench main body (1); a drive motor (3a) which drives the wheels (4); an acceleration sensor (10) which detects the acceleration acting on the workbench; and a control unit (12) which is constructed so as to determine that an abnormality has occurred and to stop the drive motor (3a) if a sudden change in speed is detected by the acceleration sensor (10).