Precision Study of Minimal Supersymmetric Standard Model by production and decay of scalar tau lepton

Study of the production and decay of scalar tau lepton ($\st$) at future $\epem$ colliders helps to determine the value of $\tan\beta$ through the measurement of the polarization of $\tau$ lepton that arises from $\st$ decay. Key maps of the parameter space of MSSM are presented. (talk presented at the fifth workshop on Japan Linear Collider(JLC) at Kawatabi, Feb 16-17.)