A synchronizing device is provided for synchronizing a first rotatable part with a second rotatable part adjacent to the first rotatable part. The synchronizing device includes a first part provided with an engaging sleeve and a second part provided with a synchronizer ring. The synchronizing device has at least one positioning resilient member which is arranged to act upon the synchronizer ring and the second part, in order to allow a design with few parts and also to resynchronize the synchronizing ring with the second part. A transmission including such a synchronizing device is also provided.