A loose-leaf folder device includes a pair of main components. First half retaining rings and second half retaining rings are arranged on the housing of the main components. Two main components can be combined with or separated from each other. When combined together, the first half retaining ring can be combined with the first half retaining ring of the other main component to form a closed retaining ring to retain loose-leaf paper. When separated from each other, the main component along with loose-leaf paper retained by it can be separated from the other main component to form two independent parts. The second half retaining ring on the housing can rotate and can form a closed retaining ring with the corresponding first half retaining ring to retain loose-leaf paper.