A calculating portion 7a calculates a distance from the tip end of a front device to an interference prevention area, and a detection line 7m detects a moving speed of a boom 1. If the tip end of the front device comes close to the interference prevention area when the boom 1 is moving upward, control is made such that, while continuing to move the boom 1 upward, a control gain calculating portion 7h and a multiplier 7i cooperatively calculate a target speed of an arm in the arm dumping direction (interference avoiding direction) corresponding to the boom-up speed, and an input limit value calculating portion 7c, an adder 7j and a minimum value selecting portion 7f cooperatively control the arm to move in the interference avoiding direction relative to a vehicle body. Interference avoidance control enabling the tip end of the front device to be moved smoothly along the vicinity of a boundary of the interference prevention area is thereby effected and the front device can be prevented from interfering with the vehicle body without reducing the maneuverability and the working efficiency.