A hydraulic brake device includes a main body, a brake lever, a hydraulic rod, a connecting rod, a sleeve member and an elastic member. The elastic member has an assembling portion, a driving portion and a deformation portion. When a user actuates the brake lever suddenly and forcefully, the driving portion of the elastic member moves toward the hydraulic room; a pressure of hydraulic oil pushes the driving portion so as to indirectly force the deformation portion to deform and bend, so that the deformation portion and the driving portion slightly move toward the assembling portion; thereby, a volume of hydraulic oil is smoothly pushed into a brake caliper through a hydraulic pipeline, such that the user brakes a bicycle stably, smoothly and safely.