polysiloxane compounds were dispersed with the particle size of about 10 u03bcm or less fig4 and 5 to the contrary in case of the polylactic acid resin composition in which the average content of amino group of polysiloxane compound having amino groups was more than 2 5 and the ratio of amino group to pla was more than 300 ppm comparative example 20 fig6 polysiloxane compounds were micronized as much as unobservable further this composition did not exhibit any improvement in rupture bending strain or tensile breaking strain it is believed that the reason is that since the amount of amino groups in amino containing polysiloxane compound was too high they were effectively reacted with pla and mingled in molecular orders and since the interaction of pla and the polysiloxane modified polylactic acid resin is too strong the sliding of molecules was not generated further in case of the polysiloxane modified polylactic acid resin composition using polysiloxane compound having no amino group comparative example 21 it is difficult to mix polysiloxane compound and polylactic acid compound also since mixed pellets are slippery it is very difficult to perform injection molding it would be arisen that the molded specimen exhibited surface bleed since the particles of the dispersed polysiloxane compound has a large particle size and the interface adhesion is weak as described above to achieve excellent impact strength rupture bending strain and tensile breaking strain and inhibit surface bleed it is demonstrated that the polysiloxane modified polylactic acid.