An immobilizing device (1) for immobilizing a part of a body (2) comprises a) a bag (12) filled with a granular material (15), where the bag (12) is put over the part of a body (2)； b) an outer shell (10) in which the bag is mounted； c) between the outer shell (10) and the bag (12) a hollow space (14) is formed for receiving pressured air in order to produce a force (F) on the bag (12) for immobilizing the part of a body. This device (1) has the combined advantages over known devices such as almost no absorption of x-rays； perfect fit for every kind of a part of a body； comfortable for a patient； reusable； cheap； neutral smell； very light； easy application.
