Hydraulic excavator

The invention provides a hydraulic excavator. By adopting the hydraulic excavator, the interference between an exhaust gas processing device and a balance weight is avoided, and operational falling of the balance weight when the balance weight is lifted is prevented. An auxiliary plate (200) is detachably arranged relative to the balance weight (5). When the auxiliary plate (200) is installed on the balance weight (5), the auxiliary plate (200) is overlapped with the exhaust gas processing device when overlooked. A plurality of hanging holes (HL1, HL2, HL3) are formed in the upper surface of the balance weight (5). The hanging hole (HL3) is formed in the auxiliary plate (200).