An environmentally-friendly vehicle sound generator apparatus comprising: a vehicle state sensing unit for sensing an operation state of a vehicle and adapted to sense a vehicle speed; a sound source storage unit for storing a plurality of operating sounds that can be output according to the operation state of the vehicle in the form of a sound source data; a sound source playback unit for selecting at least one of the operating sounds stored in the sound source storage unit, and playing back the selected sound source output from the sound source storage unit; a sound source amplification unit for amplifying the operating sound played back by the sound source playback unit; a sound output unit for outputting the operating sound amplified by the sound source amplification unit; and a control unit for receiving a sensing signal from the vehicle state sensing unit and controlling the operation of the sound source playback unit so as to play back the operating sound in such a manner as to control and change the operating sound according to the received sensing signal, wherein the control unit is adapted to: determine if the sensed vehicle speed reaches a preset speed range, and execute a fade-out function, if the sensed vehicle speed reaches the preset speed range, wherein the fade-out function comprises a fade-out speed mode reducing the sound output of the sound output unit based on a fade-out vehicle speed and a fade-out time mode reducing the output of the sound output unit over time, wherein the control unit is adapted to compare the vehicle speed with a preset fade-out mode determination speed, and wherein the fade-out speed mode is executed if the vehicle speed is less than the preset fade-out mode determination speed and the fade-out time mode is executed if the vehicle speed is greater than the preset fade-out mode determination speed, and wherein the control unit is adapted to: in the fade-out speed mode, update and calculate a fade-out vehicle speed by averaging the vehicle speed input during a preset holding time, and reduce the output of the sound output unit at a preset fade-out speed ratio according to the fade-out vehicle speed, and in the fade-out time mode, reduce the output of the sound output unit at a preset fade-out time ratio according to a time elapsed after the vehicle speed enters a range higher than the preset fade-out mode determination speed. a vehicle state sensing unit for sensing an operation state of a vehicle and adapted to sense a vehicle speed; a sound source storage unit for storing a plurality of operating sounds that can be output according to the operation state of the vehicle in the form of a sound source data; a sound source playback unit for selecting at least one of the operating sounds stored in the sound source storage unit, and playing back the selected sound source output from the sound source storage unit; a sound source amplification unit for amplifying the operating sound played back by the sound source playback unit; a sound output unit for outputting the operating sound amplified by the sound source amplification unit; and a control unit for receiving a sensing signal from the vehicle state sensing unit and controlling the operation of the sound source playback unit so as to play back the operating sound in such a manner as to control and change the operating sound according to the received sensing signal, wherein the control unit is adapted to: determine if the sensed vehicle speed reaches a preset speed range, and execute a fade-out function, if the sensed vehicle speed reaches the preset speed range, determine if the sensed vehicle speed reaches a preset speed range, and execute a fade-out function, if the sensed vehicle speed reaches the preset speed range, wherein the fade-out function comprises a fade-out speed mode reducing the sound output of the sound output unit based on a fade-out vehicle speed and a fade-out time mode reducing the output of the sound output unit over time, wherein the control unit is adapted to compare the vehicle speed with a preset fade-out mode determination speed, and wherein the fade-out speed mode is executed if the vehicle speed is less than the preset fade-out mode determination speed and the fade-out time mode is executed if the vehicle speed is greater than the preset fade-out mode determination speed, and wherein the control unit is adapted to: in the fade-out speed mode, update and calculate a fade-out vehicle speed by averaging the vehicle speed input during a preset holding time, and reduce the output of the sound output unit at a preset fade-out speed ratio according to the fade-out vehicle speed, and in the fade-out time mode, reduce the output of the sound output unit at a preset fade-out time ratio according to a time elapsed after the vehicle speed enters a range higher than the preset fade-out mode determination speed. in the fade-out speed mode, update and calculate a fade-out vehicle speed by averaging the vehicle speed input during a preset holding time, and reduce the output of the sound output unit at a preset fade-out speed ratio according to the fade-out vehicle speed, and in the fade-out time mode, reduce the output of the sound output unit at a preset fade-out time ratio according to a time elapsed after the vehicle speed enters a range higher than the preset fade-out mode determination speed.