The present disclosure relates to a control device and a control method for a construction machine. The control device and the control method for the construction machine according to the exemplary embodiment of the present disclosure may adjust an engine revolutions per minute (rpm) according to a load applied to the construction machine, thereby controlling an output of equipment. In the control device and the control method for the construction machine according to the exemplary embodiment of the present disclosure, an output of a pump is increased at an appropriate time, so that good operation performance may be maintained, and in the case of an operation pattern, in which a load is low, the engine rpm is adjusted to be decreased, thereby improving fuel efficiency.