A work machine pump control system equipped with at least one actuator driving a driven member , a hydraulic pump that is a variable displacement type and of a bent axis type and that delivers a hydraulic fluid for driving the actuators , at least one control valve controlling the hydraulic fluid to be supplied to a corresponding actuator from the hydraulic pump , at least one pilot operation type operation device generating an operation pressure (px) in accordance with an operation and outputting the operation pressure (px) thus generated to a corresponding control valve , a pilot pump generating an initial pressure of the operation pressure (px), at least one operation pressure sensor (7; 107) detecting an operation pressure (px) of a corresponding operation device , and at least one load pressure sensor (6; 106) detecting the pressure of a line connecting the hydraulic pump and the actuators as a load pressure (py), characterized in that the work machine pump control system comprises: a pump horsepower control valve that causes a first urging force determining a limited horsepower (F) of the hydraulic pump and a second urging force due to a delivery pressure of the hydraulic pump to act on a spool in opposition to each other and that controls capacity of the hydraulic pump such that a pump absorption horsepower does not exceed the limited horsepower (F) ; a target pump flow rate computation section (42; 142) computing a target pump flow rate (Qtar) of the hydraulic pump on the basis of an operation pressure (px) detected by the at least one operation pressure sensor (7; 107) and a load pressure (dy) detected by the load pressure sensor (6; 106); a target horsepower computation section (41; 141) that computes a required horsepower (Freq) corresponding to the detected operation pressure (px) from a relationship related to the operation pressure (px) of a corresponding operation device and that computes a target horsepower (Ftar) based on the required horsepower (Freq); and a pump horsepower control section that controls the pump horsepower control valve , based on a target pump flow rate (Qtar) computed by the target pump flow rate computation section (42; 142) and on a target horsepower (Ftar) computed by the target horsepower computation section (41; 141), such that the target pump flow rate (Qtar) is delivered with the limited horsepower (F) determined by the pump horsepower control valve . a pump horsepower control valve that causes a first urging force determining a limited horsepower (F) of the hydraulic pump and a second urging force due to a delivery pressure of the hydraulic pump to act on a spool in opposition to each other and that controls capacity of the hydraulic pump such that a pump absorption horsepower does not exceed the limited horsepower (F) ; a target pump flow rate computation section (42; 142) computing a target pump flow rate (Qtar) of the hydraulic pump on the basis of an operation pressure (px) detected by the at least one operation pressure sensor (7; 107) and a load pressure (dy) detected by the load pressure sensor (6; 106); a target horsepower computation section (41; 141) that computes a required horsepower (Freq) corresponding to the detected operation pressure (px) from a relationship related to the operation pressure (px) of a corresponding operation device and that computes a target horsepower (Ftar) based on the required horsepower (Freq); and a pump horsepower control section that controls the pump horsepower control valve , based on a target pump flow rate (Qtar) computed by the target pump flow rate computation section (42; 142) and on a target horsepower (Ftar) computed by the target horsepower computation section (41; 141), such that the target pump flow rate (Qtar) is delivered with the limited horsepower (F) determined by the pump horsepower control valve . <EOS>