A construction machine comprising: an engine; a hydraulic pump driven by the engine; an arm cylinder driven by pressure oil discharged from the hydraulic pump; an arm operated by extension and shrinkage of the arm cylinder; a front mechanism (31, 33, 35) including the arm and a work attachment attached to a tip of the arm; an operating device for operating the arm; and a control device for controlling a flow rate of the hydraulic pump based on an operation amount of operation by the operating device; characterized in that the construction machine includes: a posture sensor (32a, 34a, 37, 38) for detecting a posture of the arm; and a operation amount sensor for detecting the operation amount of the operating device, in case that the control device decides that the posture of the arm detected by the posture sensor (32a, 34a, 37, 38) has changed to a posture in a remoter position from a main body of the construction machine than a vertical position with respect to a ground, and that the operation amount detected by the operation amount sensor has changed from a maximum or nearly maximum preset operation amount to an operation amount toward a fine manipulation direction for positioning of the work attachment, the control device changes a flow rate characteristic of pressure oil in relation to discharge pressure of the hydraulic pump to a characteristic with a higher flow rate than a flow rate characteristic at time of operation with an operation amount other than the operation amount detected by the operation amount sensor, to drive the hydraulic pump. an engine; a hydraulic pump driven by the engine; an arm cylinder driven by pressure oil discharged from the hydraulic pump; an arm operated by extension and shrinkage of the arm cylinder; a front mechanism (31, 33, 35) including the arm and a work attachment attached to a tip of the arm; an operating device for operating the arm; and a control device for controlling a flow rate of the hydraulic pump based on an operation amount of operation by the operating device; characterized in that the construction machine includes: a posture sensor (32a, 34a, 37, 38) for detecting a posture of the arm; and a operation amount sensor for detecting the operation amount of the operating device, a posture sensor (32a, 34a, 37, 38) for detecting a posture of the arm; and a operation amount sensor for detecting the operation amount of the operating device, in case that the control device decides that the posture of the arm detected by the posture sensor (32a, 34a, 37, 38) has changed to a posture in a remoter position from a main body of the construction machine than a vertical position with respect to a ground, and that the operation amount detected by the operation amount sensor has changed from a maximum or nearly maximum preset operation amount to an operation amount toward a fine manipulation direction for positioning of the work attachment, the control device changes a flow rate characteristic of pressure oil in relation to discharge pressure of the hydraulic pump to a characteristic with a higher flow rate than a flow rate characteristic at time of operation with an operation amount other than the operation amount detected by the operation amount sensor, to drive the hydraulic pump.