A hydraulic machine including a plurality of hydraulic actuators that are driven by oil ejected from a variable displacement type hydraulic pump driven by an engine and a control device, the hydraulic machine further including means for controlling an ejection amount from the hydraulic pump, pump control means for controlling the hydraulic pump to achieve a target differential pressure (ΔP) which is a target value of a differential pressure (ΔP) between an ejection pressure (P P) of the oil ejected from the hydraulic pump and a load pressure (P L) of oil supplied to the hydraulic actuators, and control pressure generating means including an electromagnetic proportional valve for generating a control pressure (Pc) for changing the target differential pressure (ΔP), the control device being configured so that, in driving each of the hydraulic actuators, a flow rate of the oil ejected from the hydraulic pump is controlled in such a manner as to satisfy a required flow rate (Q R) of the hydraulic actuator, a control output is performed to correct a ratio (R q) of a supply flow rate with respect to the required flow rate (Q R) of the hydraulic actuator according to a change in an engine rotation number, and the control pressure (Pc) is generated by the electromagnetic proportional valve to change the target differential pressure (ΔP), characterized in that the control device is configured to set a value of the control output as a basic control output value and to control the electromagnetic proportional valve to generate the control pressure (Pc) based on a pump ejection amount control output value obtained by adding a correction amount (α2) to the basic control output value, and in a case where a change in a specific environment state quantity is a factor causing a decrease in an engine output, the environment state quantity is set as an engine output environment state quantity, a state where the engine output environment state quantity is a reference value is set as a reference environment condition, and the correction amount (α2) is a numerical value obtained by multiplying a basic correction amount (α1) determined under the reference environment condition by a correction rate (β) determined based on a measured value of the engine output environment state quantity. means for controlling an ejection amount from the hydraulic pump, pump control means for controlling the hydraulic pump to achieve a target differential pressure (ΔP) which is a target value of a differential pressure (ΔP) between an ejection pressure (P P) of the oil ejected from the hydraulic pump and a load pressure (P L) of oil supplied to the hydraulic actuators, and control pressure generating means including an electromagnetic proportional valve for generating a control pressure (Pc) for changing the target differential pressure (ΔP), the control device being configured so that, in driving each of the hydraulic actuators, a flow rate of the oil ejected from the hydraulic pump is controlled in such a manner as to satisfy a required flow rate (Q R) of the hydraulic actuator, a control output is performed to correct a ratio (R q) of a supply flow rate with respect to the required flow rate (Q R) of the hydraulic actuator according to a change in an engine rotation number, and the control pressure (Pc) is generated by the electromagnetic proportional valve to change the target differential pressure (ΔP), characterized in that the control device is configured to set a value of the control output as a basic control output value and to control the electromagnetic proportional valve to generate the control pressure (Pc) based on a pump ejection amount control output value obtained by adding a correction amount (α2) to the basic control output value, and in a case where a change in a specific environment state quantity is a factor causing a decrease in an engine output, the environment state quantity is set as an engine output environment state quantity, a state where the engine output environment state quantity is a reference value is set as a reference environment condition, and the correction amount (α2) is a numerical value obtained by multiplying a basic correction amount (α1) determined under the reference environment condition by a correction rate (β) determined based on a measured value of the engine output environment state quantity.