A wireless keyboard having a water proof mechanism includes a signal processing module and a flexible keyboard connected to one side of the signal processing module. The signal processing module includes an upper casing, a lower casing located under the upper casing, a waterproof gasket located between peripheries of the upper casing and the lower casing, and a processing unit received between the upper casing and the lower casing to emit wireless signals to a computer host. The flexible keyboard includes an upper film, a lower film hermetically connected to the upper film, and a plurality of key units electrically connected to the processing unit, wherein one common side of the upper film and the lower film is sandwiched between the upper casing and the lower casing.