To provide an armrest device convenient for an arm or a palm to be put thereon during personal computer operation or the like that has a simple and robust structure and smoothes arm motion and movement.

The armrest device is constructed such that a vertical shaft is rotatably set in an attachment fixing means for a desk or the like, horizontal linear guide bars are fixed at the upper end of the vertical shaft, sliders are adapted for linear movement along the linear guide bars, and an armrest or a palm rest is set on the sliders. The armrest or the palm rest is capable of linearly sliding and turning around the vertical shaft.