Abstract: A protective case of a foldable protective assembly defines a longitudinal direction, a width direction, and a thickness direction, which are perpendicular to each other. The protective case includes a first lower frame, a second lower frame, and two lower elastic members. Each of the first lower frame and the second lower frame has a U-shaped section perpendicular to the thickness direction. Two ends of the first lower frame respectively face two ends of the second lower frame along the longitudinal direction. The two lower elastic members respectively connect the two ends of the first lower frame to the two ends of the second lower frame. One of the first lower frame and the second lower frame is rotatable relative to the other one by elastically bending the two lower elastic members, and the protective case is configured to cover a periphery portion of a foldable mobile device.