AbstractWe have analyzed rotational spectral line emission of OCS, CH₃OH, HCOOCH₃, and H₂CS observed toward the low-mass Class 0 protostar IRAS 16293–2422 (Source A and B) at a sub-arcsecond resolution with ALMA. Significant chemical differentiation is found at a 50 au scale. OCS is found to trace the infalling-rotating envelope, while COM distributions are concentrated around the inner part of the envelope. The kinematic structure in Source A is explained with a ballistic model, and the protostellar mass and the radius of the centrifugal barrier are evaluated to be ~0.75 M_⊙ and ~50 au, respectively. This study has revealed that the centrifugal barrier plays a central role not only in the disk formation but also in the associated chemical evolution.