Dehumidifying device and lamp

A lamp comprising:

• a light source;
• a housing that contains the light source;
• a lens that outputs light from the light source to an outside of the housing;
• a ventilating member that is provided at a first position in a surface direction in which a wall extends on the wall of the housing separating an inside and the outside of the housing that is closed, the ventilating member including a ventilating film, the ventilating film preventing a liquid and a solid from entering the inside of the housing, the ventilating film circulating a gas between the inside and the outside of the housing;
• and
• an electrolysis dehumidifying element that is provided at a second position in the surface direction on the wall of the housing different from the first position, the electrolysis dehumidifying element discharging water vapor inside of the housing to the outside of the housing by electrolysis,
• wherein the first position and the second position are different areas on the wall of the housing.