A closure device for securing an electronic device on a holding device is provide. The closure device includes a first closure part having a first attaching part, a second closure part having a second attaching part and which can be attached to the first closure part in a closing direction, wherein at least one thread is arranged on one of the attaching parts and at least one engaging element is arranged on the other of the attaching parts for running onto the at least one thread when attaching the closure parts to one another, and a magnetic device that acts in a magnetically attracting manner between the first closure part and the second closure part during the attaching process.