The present invention provides a sheath for a disposable dental direct imaging digital device. The sheath for a disposable dental direct imaging digital device includes a bag structure that is made up of an elastic material, and is also made up of a positioning device that is placed in an opening of the bag structure. A direct imaging digital device may be inserted into the sheath. A first housing segment that is in connection with the opening exists on one end of the bag structure. The other end of the first housing segment is in connection with a second housing segment. A tapered channel is formed from the opening of the first housing segment towards the second housing segment. A positioning device may close or shrink the opening, so as to prevent the direct imaging digital device from sliding out of the sheath. The direct imaging digital device may be inserted into the first housing segment, and then may be inserted into the second housing segment. Accordingly, the direct imaging digital device may be encapsulated and positioned by the second housing segment. In accordance with the present invention, the time of insertion the direct imaging digital device into the sheath may be shortened, and ease of use of the sheath with the direct imaging digital device may be enhanced. Moreover, the sheath of the present invention may be suitable for a direct imaging digital device of any size.
