A keystroke device of a piano capable of increasing an area for the adjustment of static loads applied to the tips of keys on the playing sides, wherein a first weight lever (31) rotating according to the movement of the keys (21) is installed above the keys (21) and near an action part (25) and a second weight lever (41) rotating according to the movement of the first weight lever (31) is installed above the first weight lever. Since the second weight lever (41) can be separated from the action part (25), the degree of freedom of the shape and installation of the second weight lever (41) can be increased. Accordingly, the area for the adjustment of the static loads applied to the tips of the keys (21) on the playing sides can also be increased.