The connecting module is converted to a third state from a first state through a second state. The connecting module includes a fourth part, a first part, a second part and a third part, which are sequentially disposed in an axial direction. The first part is fixed to the third part. From the first state to the third state, the fourth part rotates together with the first part. From the first state to the second state, the first part rotates with respect to the second part, and the second part moves with respect to the third part in the axial direction.