An emergency stop apparatus for a working machine , comprising: a detecting device for detecting an obstacle intruding into a predetermined area around a working machine ; an actuator fixable to a vehicle body of the working machine or a member attached to the vehicle body ; a coupling member for coupling an output shaft of the actuator and a brake pedal (BP); an electronic control unit for actuating the actuator and moving the brake pedal (BP) in an actuation direction of a service brake when the obstacle is detected by the detecting device ; and characterised in that the actuator is a power cylinder and the emergency stop apparatus further comprises: a member to be detected mounted on an output shaft of the power cylinder ; and at least one sensor for detecting the member to be detected, the at least one sensor fixable to the vehicle body of the working machine or a member attached to the vehicle body such that an actuation area of the power cylinder defines at least one of a state in which the output shaft is contracted and the service brake is released, and a state in which the output shaft is extended and the service brake is actuated; wherein the actuation area of the power cylinder can be changed arbitrarily by mounting the at least one sensor to positions adapted for the characteristics of the working machine; and wherein the electronic control unit controls the actuation of the power cylinder in response to an output signal of the at least one sensor . a detecting device for detecting an obstacle intruding into a predetermined area around a working machine ; an actuator fixable to a vehicle body of the working machine or a member attached to the vehicle body ; a coupling member for coupling an output shaft of the actuator and a brake pedal (BP); an electronic control unit for actuating the actuator and moving the brake pedal (BP) in an actuation direction of a service brake when the obstacle is detected by the detecting device ; and characterised in that the actuator is a power cylinder and the emergency stop apparatus further comprises: a member to be detected mounted on an output shaft of the power cylinder ; and at least one sensor for detecting the member to be detected, the at least one sensor fixable to the vehicle body of the working machine or a member attached to the vehicle body such that an actuation area of the power cylinder defines at least one of a state in which the output shaft is contracted and the service brake is released, and a state in which the output shaft is extended and the service brake is actuated; wherein the actuation area of the power cylinder can be changed arbitrarily by mounting the at least one sensor to positions adapted for the characteristics of the working machine; and wherein the electronic control unit controls the actuation of the power cylinder in response to an output signal of the at least one sensor . a member to be detected mounted on an output shaft of the power cylinder ; and at least one sensor for detecting the member to be detected, the at least one sensor fixable to the vehicle body of the working machine or a member attached to the vehicle body such that an actuation area of the power cylinder defines at least one of a state in which the output shaft is contracted and the service brake is released, and a state in which the output shaft is extended and the service brake is actuated; wherein the actuation area of the power cylinder can be changed arbitrarily by mounting the at least one sensor to positions adapted for the characteristics of the working machine; and wherein the electronic control unit controls the actuation of the power cylinder in response to an output signal of the at least one sensor . <EOS>