A crossbow includes a body and an activator. The body has a shooting device, a first safety device and a string connected thereto. The shooting device has a trigger. The activator is located at the rear end of the body and has an extension. A second safety device is located between the extension and the body, and includes a rod and contact member. When the activator is operated, the activator is removed from the rod which pivots the contact member, and the contact member contacts the first safety device to restrict the trigger from being pulled. When the activator is not operated and positioned at the body, the rod is pushed by the activator and pivots the contact member, and the first safety device is released so that the trigger can be pulled.