  We study Higgs boson decays in the minimal supersymmetric standard model
where the tree-level CP invariance of the Higgs potential is explicitly broken
by loop effects of soft CP-violating Yukawa interactions related to scalar
quarks of the third generation. The scalar-pseudoscalar mixing among two
neutral CP-even Higgs bosons and one CP-odd Higgs boson due to explicit CP
violation modifies their tree-level couplings to fermions, to the W^\pm and Z
bosons and to Higgs bosons themselves significantly. We analyze the
phenomenological impact of explicit CP violation on the branching ratios of the
neutral Higgs boson decays in detail and discuss how to directly confirm the
existence of explicit CP violation through \tau^+ \tau^- and t \bar{t} spin
correlations in the decays of the neutral Higgs bosons into a tau-lepton pair
and a top-quark pair.
