A polylactic acid that contains a stereocomplex crystal, excelling in moldability and that has a high molecular weight, high crystallinity and high melting point; and a process for producing the same. Further, there are provided a composition of the polylactic acid and a molding thereof. In particular, there is provided a polylactic acid of 8 to 50*10⁴ weight average molecular weight wherein in the measurement by means of differential scanning calorimeter (DSC), the ratio of 195 DEG C melting peak to all melting peaks during temperature rise step is 80%, and provided a process for producing the same.