  We study the baryon asymmetry of the universe in the supersymmetric standard
model (SSM). At the electroweak phase transition, the fermionic partners of the
charged SU(2) gauge bosons and Higgs bosons are reflected from or transmitted
to the bubble wallof the broken phase. Owing to a physical complex phase in
their mass matrix, these reflections and transmissions have asymmetries between
CP conjugate processes. Equilibrium conditions in the symmetric phaseare then
shifted to favor a non-vanishing value for the baryon number density, which is
realized through electroweak anomaly. We show that the resultant ratio of
baryon number to entropy is consistent with its present observed value within
reasonable ranges of SSM parameters, provided that the CP-violating phase
intrinsic in the SSM is not much suppressed. The compatibility with the
constraints on the parameters from the electric dipole moment of the neutron is
also discussed.
