The timbre of violins has been studied by several researchers from various points of view including the structure, the acoustic characteristic, the chemical composition of the varnish and the acoustic radiation. Although many of them have mentioned that the Stradivari’s violin gives the most beautiful timbre, the reasons of which have not been clarified yet. We have studied the timbre of about 30 violins from old ones to new ones, namely, the relation between the harmonic overtones and the expression words, which the audience receives from the sound of violin. But, we have not been successful in clarifying how the structure of overtone is related with the feeling of the listeners of sound such as “rich”, “blight” and “soft” as the timbre of violin. In this paper, we have analyzed the change of overtone structure with the difference of violinist’s performance. For instance, the power (dB) of sound at the frequency area over 2000 Hz played in fortissimo or near a bridge like sul ponticello was approximately 10% to 20% higher than that played in pianissimo or on finger board such as sul tast. We also found that the power of non-harmonic overtone of the sound which was played in the “rich” or “soft” expression was high at the frequency area over 2000 Hz and the kurtosis of the peak of harmonic overtone was small.