An upright piano type action comprising: a jack moving in response to a depression and a release of a key; a butt having a surface pushed up by the jack in response to the depression of the key; and a swinging member extending from the butt and, to perform a hitting activity, swinging, thereby defining a forward direction, in response to the depression of the key and swinging, thereby defining a backward direction, in response to the release of the key; wherein the surface of the butt is provided with a curved slanting pressure receiving portion which is situated backward and another, curved portion which is situated forward and has an inclination angle with respect to the horizontal plane smaller than the inclination angle of a respective tangent plane of the slanting pressure receiving portion with respect to the horizontal plane as areas pushed up by the jack, so that the other portion and the slanting pressure receiving portion form an escapement portion having an obtuse angle between the other portion and the slanting pressure receiving portion; and the escapement portion is provided to correspond to a position of the jack placed immediately after start of swinging caused by contact of the jack with a regulating member in some point during the depression of the key; the other portion is a flat portion, and in that the angle of inclination of the respective tangent plane of the slanting pressure receiving portion is such that when the key is depressed to a full stroke position so slowly that the swinging member will not perform the hitting activity, the jack is to continue pushing up the butt, whereas in a stage where the key starts returning from the full stroke position, a position at which the butt is in contact with the jack is kept with the butt swinging backward, characterized in that the angle of inclination between the horizontal plane and the respective tangent plane of the slanting pressure receiving portion at the position where the jack is in contact with the slanting pressure receiving portion when the key is depressed to a full stroke position so slowly that the swinging member will not perform the hitting activity, is from 15 to 33 degrees. a jack moving in response to a depression and a release of a key; a butt having a surface pushed up by the jack in response to the depression of the key; and a swinging member extending from the butt and, to perform a hitting activity, swinging, thereby defining a forward direction, in response to the depression of the key and swinging, thereby defining a backward direction, in response to the release of the key; wherein the surface of the butt is provided with a curved slanting pressure receiving portion which is situated backward and another, curved portion which is situated forward and has an inclination angle with respect to the horizontal plane smaller than the inclination angle of a respective tangent plane of the slanting pressure receiving portion with respect to the horizontal plane as areas pushed up by the jack, so that the other portion and the slanting pressure receiving portion form an escapement portion having an obtuse angle between the other portion and the slanting pressure receiving portion; and the escapement portion is provided to correspond to a position of the jack placed immediately after start of swinging caused by contact of the jack with a regulating member in some point during the depression of the key; the other portion is a flat portion, and in that the angle of inclination of the respective tangent plane of the slanting pressure receiving portion is such that when the key is depressed to a full stroke position so slowly that the swinging member will not perform the hitting activity, the jack is to continue pushing up the butt, whereas in a stage where the key starts returning from the full stroke position, a position at which the butt is in contact with the jack is kept with the butt swinging backward, characterized in that the angle of inclination between the horizontal plane and the respective tangent plane of the slanting pressure receiving portion at the position where the jack is in contact with the slanting pressure receiving portion when the key is depressed to a full stroke position so slowly that the swinging member will not perform the hitting activity, is from 15 to 33 degrees.