A vehicular lamp having an air vent structure of reduced size and with which the airtightness of a lamp housing can easily be tested. An integrally formed tubular wall projects rearward from a rear wall of a lamp body. The rear edge of the tubular wall is inclined downward in a forward direction, and its outward edge lies in a single plane inclined downward in the forward direction. A communicating hole through which the interior and exterior of a lamp housing are communicated is formed in a portion of the rear wall which is surrounded by the tubular wall.