The invention relates to a forearm massaging device of a massage chair, and belongs to the technical field of structures of massaging devices. The forearm massaging device of the massage chair is characterized by being arranged in an armrest of the massage chair and comprising an armrest main body, wherein an armrest lifting button is arranged outside the armrest main body; the upper surface of the armrest main body is provided with an opening through which a forearm massager passes; a fixed supporting mechanism is arranged in the armrest main body and connected with a driving mechanism and a sliding mechanism which is connected with the driving mechanism and driven to move up and down by the driving mechanism; and the upper part of the sliding mechanism is connected with the forearm massager which moves synchronously with the sliding mechanism. The forearm massaging device of the massage chair has a reasonable structure, is safe and convenient to operate, can massage forearms and descend the forearm massager to hide the forearm massager in the armrest when the forearms are not massaged, solves the problem that the forearm massager occupies space when not used, and also improves the whole appearance effect of the massage chair.