The present invention relates to a method for manufacturing a musical instrument, in which method a musical instrument is manufacturing for one or several parts and of which parts at least one part is manufactured of plastic material compound, which includes thermoplastic polymer. The present invention relates also to a musical instrument, which instrument has been manufactured of one or several parts and of which parts at least a part has been manufactured of plastic material compound, which includes thermoplastic polymer. Characteristic to the method in accordance with the invention is the fact that plastic material compound is made by mixing natural fibers to thermoplastic polymer and that a musical instrument or its parts are manufactured of plastic material compound by injection moulding such that the natural fibers in plastic material compound are directed mainly in certain, desired direction in respect of the musical instrument or its part while moulding. Characteristic to the musical instrument in accordance with the invention is the fact that the musical instrument or its parts have been made of thermoplastic polymer, with natural fibers mixed to it, and that in the musical instrument or part of it natural fibers have directed mainly in certain, desired direction in respect of the musical instrument or its part.