A reinforcing bar binding machine is provided with a control unit operated in such a manner that at the time of turning on an electric power source switch, a setting position of a motor drive adjustment dial and a state of a trigger lever are read, and when the motor drive adjustment dial is at a specific setting position and when the trigger lever is turned on, a binding wire cutting mechanism is driven by a predetermined number of times for warming up the binding wire cutting mechanism. When the warming-up operation is carried out in a cold environment, it is possible to reduce the viscosity of grease coated on a mechanism portion. Therefore, it is possible to lower a viscosity of grease applied on a mechanical portion and conduct a reinforcing bar binding work without wasting a binding wire in the same manner as that in a warm environment.