The present invention provides a humidifier capable of removing microorganisms without using electric power. The humidifier includes a reservoir; a humidification system including a humidification filter arranged such that at least part thereof is immersed in water and a blowing means for discharging air through the humidification filter; and a microorganism remover including a first electrode and a second electrode having different electric potentials and opposing to each other to have a space therebetween and a short circuit part for causing a short circuit between the first and second electrodes. The first electrode is higher than the second electrode in electric potential and at least the first and second electrodes are arranged in contact with water in the reservoir.