A hydraulic driving system includes first to third liquid-pressure pumps and control valves. The first boom control valve is connected to the first hydraulic pump, and the second arm control valve and the first bucket control valve are connected to the second liquid-pressure pump. Further, the turning control valve and the second bucket control valve are connected to the third hydraulic pump. When a pilot pressure XAk0 is output from a bucket operating device while a turning operation is performed, a command switching device outputs a pilot pressure XAk1 to the first bucket control valve. When the pilot pressure XAk0 is output from the bucket operating device while the turning operation is performed, the command switching device outputs a pilot pressure XAk2 to a second bucket control valve.