Abstract: A bearing structure in a piano action part which can always maintain the torque of rotation of a pin shaft supporting a hammer member within a predetermined range characterized in that the bearing structure comprises a pin shaft fixed to a hammer member, a support member having through-holes through which the pin shaft passes and cloth members with which the spaces between the through-holes and the pin shaft inserted through the through-hole are packed, and that the support member is made of a cellulose derivative resin composition containing silica having a number of silanol groups of 3.0 or less per 100 square .ANG. and a BET specific surface area of 100 to 210 m.sup.2 /g, and a transmission structure in a piano characterized in that the transmission structure comprises a hammer member and the above-mentioned bearing structure.

Abstract: A black key making of a resin composition comprising a cellulose derivative resin, silicon oxide and at least 0.3 part by weight of a carbon black based on 100 parts by weight of the cellulose derivative, the carbon black having a pH of 6 and below and a BET specific surface area of 260 m.sup.2 /g and above, a keyboard comprising white keys and above-described black keys and a musical instrument having the above-described keyboard are disclosed. The black key is excellent in productivity and processability and is hygroscopic and excellent in the touch to fingers during playing. The black key is preferably made by injection molding.

Abstract: A keyboard for a musical instrument is composed of a resin composition, having a durometer hardness of 82 or larger, and the composition comprises a cellulose derivative resin and a silica having 3.0 or less silanol groups in the area of 100 square angstrom and a BET specific surface area of 10 to 210 m.sup.2 /g. It may comprises a substrate and the keyboard.