Action of grand piano

An action of a grand piano, which operates in accordance with depression of a key to thereby cause pivotal motion of a hammer, including:

• a wippen formed by a molded article of a synthetic resin and configured to pivotally move upward by being pushed up by the key subjected to key depression;
• a jack pivotally mounted to the wippen and configured to push up the hammer in accordance with pivotal motion of the wippen to cause the hammer to pivotally move upward;
• and
• a jack angular position-adjusting mechanism provided on the wippen so as to adjust an angular position of the jack,
• wherein the jack angular position-adjusting mechanism comprises:
• a support portion integrally formed with the wippen;
• an adjustment screw extending a predetermined length in a front-rear direction and screwed into the support portion such that the adjustment screw is movable forward and backward in the front-rear direction;
• and
• an abutment portion provided on a jack-side end of the adjustment screw, for defining the angular position of the jack by abutment with the jack.