A fluid applicator includes a tubular container having a top open end and a bottom open end, a floating stopper mounted in the tubular container for sealing the bottom open end of the tubular container, a fluid filled in between the top open end and bottom open end of the tubular container, and a plug for closing the top open end of the tubular container. When the plug is opened from the top open end of the tubular container for allow the atmospheric pressure to enter the tubular container, the floating stopper is forced to adhere to the peripheral wall of the tubular container for allowing the fluid to flow out of the fluid container. When the plug seals the top open end of the tubular container, the atmospheric pressure is prohibited from entering the tubular container, and the floating stopper stops the bottom open end of the tubular container again.