To provide a hydraulic circuit for a construction machine, capable of calculating a pressure difference between the upstream side and the downstream side of a regeneration valve arranged in an oil path which resupplies return oil to hydraulic actuators, and of controlling the opening of the regeneration valve on the basis of the calculated pressure difference.

The hydraulic circuit for the construction machine for controlling the operation of the plurality of hydraulic actuators includes detection means 23 for detecting first driving pressure of pressure oil supplied to one hydraulic actuator and second driving pressure of pressure oil supplied to the other hydraulic actuator, a regenerative circuit 24 for resupplying return oil from one hydraulic actuator, and control means 30 for controlling a hydraulic pump, the detection means and the regenerative circuit. The regenerative circuit includes a regeneration valve 24Vth provided in the oil path which resupplies the return oil, and the control means includes a pressure difference calculation part for calculating a pressure difference between hydraulic oil pressure on the upstream side of the regeneration valve and hydraulic oil pressure on the downstream side thereof on the basis of a load pressure difference between the first driving pressure and the second driving pressure. It controls the opening of the regeneration valve on the basis of the calculated pressure difference.