Abstract: A protective shell includes a shell body and support elements. The shell body covers an electronic device and includes a space for receiving the support elements. The support elements include a first support arm and a second support arm. The second support arm includes a first free end rotatably received in the receiving space and a second free end. The first support arm includes a third receiving space, a first end and a second end. The third receiving space can receive the second free end. The first end is slidably received in the second receiving space. The second end can be pulled out of the second receiving space toward outside of the shell body. An angle of the support element given to the shell body is adjustable because of the articulation between the first support arm and a second support arm.