A hydraulic excavator comprising: a self-propelled lower traveling structure; an upper revolving structure mounted rotatably on the lower traveling structure; and a working mechanism mounted tiltably on a front side of the upper revolving structure; the upper revolving structure comprising: a revolving frame on whose front side the working mechanism is mounted; an operator's seat disposed on a front side of the revolving frame; a right front cover disposed from the right side of the operator's seat toward a front end side of the revolving frame and covering equipment mounted on the revolving frame; a control valve device controlling supply and discharge of pressurized oil to a plurality of hydraulic actuators provided on the lower traveling structure, the upper revolving structure and the working mechanism; and an accumulator accumulating the pressure of the pressurized oil discharged from at least one hydraulic actuator in the plurality of hydraulic actuators and having a pressurized oil supply and discharge port connected to the control valve device, characterized in that: an accumulator support device (23, 33) supporting the accumulator is provided between the operator's seat and the right front cover, wherein the accumulator support device (23, 33) is configured by a box (24, 34) providing the inside thereof for an accommodating space (25, 35) accommodating the accumulator and having an opening (26, 36) taking the accumulator in and out of the accommodating space (25, 35) and a lid member (28, 37) whose one end is rotatably connected to the box (24, 34) by a connecting member and opened and closed between an open position at which the opening (26, 36) is opened and a closed position at which the opening (26, 36) is closed, and the accumulator is configured to be mounted on the lid member (28, 37) in the state where the pressurized oil supply and discharge port is disposed on the connecting member side. a self-propelled lower traveling structure; an upper revolving structure mounted rotatably on the lower traveling structure; and a working mechanism mounted tiltably on a front side of the upper revolving structure; the upper revolving structure comprising: a revolving frame on whose front side the working mechanism is mounted; an operator's seat disposed on a front side of the revolving frame; a right front cover disposed from the right side of the operator's seat toward a front end side of the revolving frame and covering equipment mounted on the revolving frame; a control valve device controlling supply and discharge of pressurized oil to a plurality of hydraulic actuators provided on the lower traveling structure, the upper revolving structure and the working mechanism; and an accumulator accumulating the pressure of the pressurized oil discharged from at least one hydraulic actuator in the plurality of hydraulic actuators and having a pressurized oil supply and discharge port connected to the control valve device, a revolving frame on whose front side the working mechanism is mounted; an operator's seat disposed on a front side of the revolving frame; a right front cover disposed from the right side of the operator's seat toward a front end side of the revolving frame and covering equipment mounted on the revolving frame; a control valve device controlling supply and discharge of pressurized oil to a plurality of hydraulic actuators provided on the lower traveling structure, the upper revolving structure and the working mechanism; and an accumulator accumulating the pressure of the pressurized oil discharged from at least one hydraulic actuator in the plurality of hydraulic actuators and having a pressurized oil supply and discharge port connected to the control valve device, an accumulator support device (23, 33) supporting the accumulator is provided between the operator's seat and the right front cover, wherein the accumulator support device (23, 33) is configured by a box (24, 34) providing the inside thereof for an accommodating space (25, 35) accommodating the accumulator and having an opening (26, 36) taking the accumulator in and out of the accommodating space (25, 35) and a lid member (28, 37) whose one end is rotatably connected to the box (24, 34) by a connecting member and opened and closed between an open position at which the opening (26, 36) is opened and a closed position at which the opening (26, 36) is closed, and the accumulator is configured to be mounted on the lid member (28, 37) in the state where the pressurized oil supply and discharge port is disposed on the connecting member side.