An optical module, including a first frame, a second frames, an optical element, a first driving module, and a second driving module, is provided. The first frame is connected to a base. The second frame is connected to and located in the first frame. The optical element is disposed in the second frame. The first driving module is disposed between the base and the first frame to drive the first frame to oscillate around a first rotating axis. The second driving module is disposed between the first and second frames to drive the second frame to oscillate around a second rotating axis. The first and second rotating axes are perpendicular to an optical axis of the optical element, and not parallel. An overall dimension of the second driving module is less than that of the first driving module. A projection device having the optical module is also provided.