A humidifier for fuel cell of the present invention comprises a hollow fiber membrane module in which a hollow fiber membrane bundle, comprising hollow fiber membranes bundled together, is accommodated inside a housing. The module comprises an entrance head which supplies off-gas inside the hollow fiber membranes, an exit head which converges off-gas, which has passed through the hollow fiber membranes, at another end of the hollow fiber membrane module, and an exhaust exit which exhausts liquid, accumulated in the entrance head. According to this humidifier, it is possible to prevent the hollow fiber membranes from becoming blocked by water.