A bicycle handbrake operating device is provided. The present invention utilizes a roller wheel to pull the brake wire so as to generate a longer pulling distance and to reduce the exerted force as well. The roller wheel is installed inside the handbrake operating device, and the brake wire goes around the roller wheel. When the operating lever is gripped, the brake wire slides along the roller wheel to achieve a longer pulling distance; the roller wheel's self rotation also reduces the exerted force. Additionally, the brake wire almost always remains a straight line during the pull, which makes the operation of the handbrake operating device smooth and the brake wire would undergo minimum wearing.