An aircraft actuator hydraulic system that includes hydraulically operated actuators for driving control surfaces of an aircraft and that supplies pressure oil to the actuators, the system comprising: a first actuator that is provided as one of the actuators and that drives a first control surface provided as one of the control surfaces by being operated by supply of pressure oil from a first aircraft central hydraulic power source with a first air cooler; a second actuator that is provided as another one of the actuators and that drives a second control surface provided as another one of the control surfaces and provided so as to operate in pairs with the first control surface or that drives the first control surface by being operated by supply of pressure oil from a second aircraft central hydraulic power source with a second oil cooler; a first backup hydraulic pump that can supply pressure oil to the first actuator when a loss or degradation in a function of the first aircraft central hydraulic power source occurs; a second backup hydraulic pump that can supply pressure oil to the second actuator when a loss or degradation in a function of the second aircraft central hydraulic power source occurs; and a controller (12a, 12b) that, when a loss or degradation in the function of one of the first aircraft central hydraulic power source and the second aircraft central hydraulic power source occurs, performs a control so as to operate the other backup hydraulic pump, out of the first backup hydraulic pump and the second backup hydraulic pump, which is connected downstream of the other hydraulic power source, which is the other of the first aircraft central hydraulic power source and the second aircraft central hydraulic power source, wherein oil flowing through the other backup hydraulic pump and the other hydraulic power source is cooled by the oil cooler of the other hydraulic power source by operation of the other backup hydraulic pump under control of the controller in a state where the other hydraulic power source is being operated. a first actuator that is provided as one of the actuators and that drives a first control surface provided as one of the control surfaces by being operated by supply of pressure oil from a first aircraft central hydraulic power source with a first air cooler; a second actuator that is provided as another one of the actuators and that drives a second control surface provided as another one of the control surfaces and provided so as to operate in pairs with the first control surface or that drives the first control surface by being operated by supply of pressure oil from a second aircraft central hydraulic power source with a second oil cooler; a first backup hydraulic pump that can supply pressure oil to the first actuator when a loss or degradation in a function of the first aircraft central hydraulic power source occurs; a second backup hydraulic pump that can supply pressure oil to the second actuator when a loss or degradation in a function of the second aircraft central hydraulic power source occurs; and a controller (12a, 12b) that, when a loss or degradation in the function of one of the first aircraft central hydraulic power source and the second aircraft central hydraulic power source occurs, performs a control so as to operate the other backup hydraulic pump, out of the first backup hydraulic pump and the second backup hydraulic pump, which is connected downstream of the other hydraulic power source, which is the other of the first aircraft central hydraulic power source and the second aircraft central hydraulic power source, wherein oil flowing through the other backup hydraulic pump and the other hydraulic power source is cooled by the oil cooler of the other hydraulic power source by operation of the other backup hydraulic pump under control of the controller in a state where the other hydraulic power source is being operated.