To provide an outdoor terminal of an air supply system capable of not only blocking intrusion of rain and wind, but also easily maintaining and managing a filter for capturing dust, small insects and the like, and further suppressing clogging of the filter and increase of pressure loss.

In this outdoor terminal of the air supply system comprising a hood 7 for collectively covering an upper part, a front part and side parts of an outdoor-side opening portion 5 of a connection cylindrical portion 4 mounted in a state of communicating with an outdoor-side opening end 3 formed on an external wall of a building, and opened downward at its lower face as an air supply port 6, the filter 10 having a front face, side faces, a lower face and a ventilation face 12 sufficiently more wider than an opening area of the air supply port 6 of the hood 7 and having the shape retaining property for preventing passing of small substances through the ventilation face 12 is connected with the air supply port 6.