The electronic device includes a body, a strap, and a strap connecting member. The strap connecting member further includes a pin, a torsion spring one end of which is connected to the pin, a receiving chamber accommodating the pin and defining an opening notch passing through the sidewall thereof, and a cover connected with the torsion spring and engaging with the receiving chamber. The strap is double-layered. The double-layered strap forms a folded end and an open end, the folded end is connected with the pin and is wrapped around the pin, and the open end is separated into two portions which pass at the opening notch and are respectively connected to the body. When the torsion spring is elastically deformed and generates a torsion force, the pin is rotated and the strap automatically shrinks in the receiving chamber under the torsion force.