The present invention provides a breather that includes a waterproof air-permeable membrane and a mounting device, the mounting device having a rod with a hollow structure and a head at one side of the rod. The head includes a bottom wall which has a circular bore in communication with the hollow portion of the rod and around which sidewalls are formed, several through holes being formed in the sidewalls, a fastening cover cooperating with the head with a chamber formed therebetween, wherein the waterproof air-permeable membrane is mounted inside the rod, and wherein the through hoes, the chamber and the circular bore communicatively connect the inside and outside of the breather.