Disclosed herein is a humidifier. The humidifier includes a rear casing, a front casing placed in front of the rear casing and having an opening formed on its front side, a fan housing having an air intake unit formed on its front side, wherein an air blower unit is formed on one side of a circumference part of the fan housing, a humidification filter placed in front of the air intake unit, and a water tank placed on a side of the humidification filter. The fan housing has a partition wall projected therefrom between the humidification filter and the water tank, and the partition wall partitions a front side of the fan housing into a space through which air passes and a space where the water tank is placed.