Drive device for working machine and working machine provided with same

Provided is a drive device that is for a working machine, is provided by a hydraulic closed circuit system that drives a cylinder by means of a hydraulic pump, and causes the movement speed in both the extending and contracting directions of a piston rod to be equivalent. The present invention is provided with: a first hydraulic pump having a flow rate adjustment means that controls the direction and flow rate of a discharged hydraulic oil; a single-rod hydraulic cylinder that is driven by hydraulic oil and that drives one working member of a working device of the working machine; a hydraulic closed circuit resulting from the first hydraulic pump and the single-rod hydraulic cylinder being connected in a closed loop by means of a duct through which the hydraulic oil flows; a branch path that branches from the duct between the first hydraulic pump and the single-rod hydraulic cylinder; a first duct of which one end side is connected to the branch path; a tank connected to the other end side of the first duct; and a hydraulic-oil-flow-rate adjustment device that is provided to the first duct and that can control the flow rate of the hydraulic oil flowing to the branch path from the tank or the flow rate of the hydraulic oil flowing from to the tank from the branch path.