A ventilation device that discharges water vapor within a housing of a vehicular lamp to the outside, and includes: an attachment part attached in communication with ventilation opening in the housing; and a ventilation path that is a hollow formed from upstream toward downstream side, and that has a bent part which bends from a first to a second direction. In ventilation path: cross-sectional area S3 of a cross section orthogonal to second direction on downstream side is constituted by making cross-sectional area S2 of a cross section orthogonal to the first direction on the entrance side of bent part larger than the cross-sectional area S1 of a cross section orthogonal to first direction on upstream side, and making the length, in first direction, on exit side of bent part shorter than the length, in second direction, of the cross-sectional area S1; thereby, cross-sectional area S1 cross-sectional area S3.

A ventilation system for a vehicle headlight housing. The ventilation body has an inner part extending into the housing opening as well as an outer part extending circumferentially about the opening wall of the housing opening, which on the one hand offers, in the locked position thereof, a sealing attachment and on the other hand provides a labyrinthic ventilation channel.

A rear lamp includes a housing, a partition part that is provided within the housing and divides the housing into a first region and a second region, a plurality of lamp units provided in the first region, and a measurement unit provided in the second region. The housing includes an opening part provided with an opening that communicates between the second region and the outside of the housing.

A rear lamp includes a housing, a partition part that is provided within the housing and divides the housing into a first region and a second region, a plurality of lamp units provided in the first region, and a measurement unit provided in the second region. The housing includes an opening part provided with an opening that communicates between the second region and the outside of the housing.