Abstract: In construction of a keyboard unit accommodable upright piano, a vertically turnable keyboard is held by a holder unit so that the keyboard unit can be stably held in a horizontal position at one state of the holder unit and easily be accommodated in the main casing at the other state of the holder unit.

Abstract: In the construction of a housing for upright pianos, as a substitute for the conventional hard, thick and heavy wooden boards associated with back posts vulnerable to circumstantial changes, soft, thin and light wooden boards are attached to a metallic skelton of a substantially rectangular construction suited for supporting a keyboard assembly. Weight of the housing is greatly reduced without impairing strength and no use of back posts makes the housing well durable against changes in environmental factors.

Abstract: A leg is coupled to one half of the connecting structure, e.g. a detachable seat, via screw engagement and the latter is coupled, via wedge engagement to be established by projections formed thereon, to the other half of the connecting structure, e.g. a fixed seat, mounted to the bottom of a massive body such as a keyboard musical instrument, a larger sized television set and a heavy table. Registration of the leg at the correct position and the above-described wedge engagement are carried out simply by sliding the one seat against the other seat with alleviated trouble in the collimation work, reduced damage on the thread construction and stabilized support for the massive body.