The purpose of the present invention is to operate an engine in a proper operation state while keeping the remaining amount in an electrical storage apparatus within a proper range. Hybrid construction machinery according to the present invention is provided with a controller for controlling an engine according to a governor characteristic having a predetermined inclination that defines a relationship between load torque and rotational speed so that the rotational speed decreases with an increase in the load torque. In the controller, a target engine power calculating unit (2-5) calculates a first target engine power that increases and decreases according to increases and decreases in output values of a load power calculating unit (2-1) and a charge/discharge request calculating unit (2-3), and a target rotational speed calculating unit (2-6) calculates, as a command value for a target rotational speed of a motor generator, a rotational speed at the intersection point of a governor characteristic line changed by a governor characteristic changing unit (2-4) and an equal power line dependent on the first target engine power on a rotating speed-torque characteristic line diagram.