A file folder includes a front panel, a rear panel, and two side expandable connecting members coupled between the front panel and the rear panel for allowing the front panel and the rear panel to be moved toward or away from each other in order to adjust a space between the front panel and the rear panel. The connecting members each include a V-shaped front connecting segment having a free end attached to the front panel with weldings, and a V-shaped rear connecting segment coupled to the front connecting segment and having a free end attached to the rear panel with weldings. One or more V-shaped intermediate connecting segments may further be coupled between the front and the rear connecting segments.