To provide an obstacle sensing system capable of sensing obstacles over a wide range around a vehicle with a small number of radar modules.

An obstacle sensing system placed on a vehicle is provided. It comprises an antenna, a direction changing means, an obstacle sensing means, and a rotation means. The antenna emits a beam of electromagnetic wave. The direction changing means is placed on a track where the beam emitted from the antenna progresses, and changes the progress direction of the beam. The obstacle detection means detects obstacles by sensing the reflection wave of the beam emitted from the antenna. The rotation means changes the progress direction of the beam by rotating at least one of the antenna and the direction changing means.