A magnetic retractable line divider may include at least a reel assembly having a shell, and a magnetic portion is installed thereon. An elastic line divider belt is wound on the reel assembly, and a magnetic member is connected to a lateral end of the line divider belt. The line divider belt is configured to be horizontally pulled out from the reel assembly and travel a preferred distance to attach to a magnetic object, thus achieving line divider effect. Moreover, when someone pushes against the line divider belt with or over a preferred force, the magnetic member is configured to be detached from the magnetic object and automatically retracted into the reel assembly, thus avoiding accident.