Construction machinery having rotating body

The present invention provides a storage device when the storage amount exceeds the appropriate value can be continued in hybrid mode operation of construction machinery. As to drive the upper rotating body (20) having a hydraulic motor (27) and the electric motor (25) both. When the capacitor (24) of the storage amount when appropriate, by a hydraulic motor (27) and the electric motor (25) to drive both of the upper slewing body (20). Switch when the capacitor (24) of the storage amount exceeds the appropriate value for the upper structure using only the hydraulic motor (27) (20) of the drive and the secondary drive or engine-driven auxiliary generator motor (23), the capacitor (24) storage capacity quickly return to an appropriate range. Enables the capacitor (24) of smaller capacity, without impairing the operability of the turning motion of the capacitor manage storage amount.