Disclosed are a mode-locked resonator according to an embodiment and an ultrashort pulse laser comprising the mode-locked resonator. The mode-locked resonator according to an embodiment includes a resonator including a shape of a sphere; and a saturable absorber coated on a surface of the resonator, wherein the resonator is coupled with some photons traveling in a tapered optical fiber disposed near the mode-locked resonator and interacts with the saturable absorber based on a Whispering Gallery Mode (WGM).