To provide construction machinery in which overload of excavation action can be determined on the basis of an excavation reaction force obtained by positions and attitudes of working elements such as a boom, arm, and bucket without a need for attaching a load detection device, thereby action of the working elements being controllable.

A controller of the construction machinery for excavation work calculates an excavation reaction force from soil acting on a bucket based on a boom angle, arm angle, bucket angle, and soil characteristics, and determines whether the calculated excavation reaction force is larger than the upper limit of the predetermined value or not in order to decide a need for modifying the excavation action.