<p>Provided is a hybrid construction machine (construction machine using an electric motor for driving a swing structure) capable of performing satisfactory operations even when trouble disabling the electric motor from outputting torque has occurred for some reason. The hybrid construction machine is equipped with both a hydraulic motor 27 and an electric motor 25 for the driving of the swing structure and a controller 80 for switching between a hydraulic/electric hybrid swing mode (using both the hydraulic motor and the electric motor) and a hydraulic-alone swing mode (using only the hydraulic motor). The switching is executed while achieving satisfactory operability and performance in each mode. Normally, an energy saving operation is performed in the hydraulic/electric hybrid swing mode. When the electric amount of an electricity storage device has gone out of a prescribed range or an abnormality has occurred in an electric system (e.g., failure of an inverter), the swing mode is switched to the hydraulic-alone swing mode so that driving with normal braking torque is possible by the hydraulic motor alone.</p>
