To provide an armrest device wherein the operability and the structure are simple, the cost is low, and play is prevented from occurring.

This armrest device comprises a fixed side member 2, an armrest 7 which is vertically movable to the fixed side member 2, and a fitting 9 for the armrest 7. The fixed side member 2 has a receiving body 4 on which a supporting body 8 from the armrest 7 can abut. Then, the receiving surface 4a of the receiving body 4 is formed into a shape having a V-shape cross sectional surface. The fitting 9 fixes the supporting body 8 by pressing it to the receiving surface 4a. Then, the fixation of the armrest 7 is performed by pressing a pair of sections of the supporting body 8 to a pair of surfaces of the receiving surface 4a, i.e., remote two locations are used as the pressing locations. Therefore, the play of the supporting body 8 can be completely prevented from occurring. The receiving body 4 has a simple structure and can be provided at a low cost. Also, the receiving body 4 can be fixed by only one fitting 9, and the operation can be simply and easily performed.