Disclosed is a ventilation device for discharging water vapor from the interior of a housing of a vehicular lamp to the outside of the housing, wherein: a ventilation path that is bent and is in communication with a ventilation opening in the housing is formed; and, up to the terminal end of the ventilation path including the bent part, the ventilation path maintains a minimum cross-sectional area with which it is possible to maintain a fogging reduction rate of 80% or higher in a lapse of 5 minutes. Thus, a defogging property inside the housing is improved while preventing the infiltration of liquid water and external substances by employing the ventilation path having a bent part.