  Considering the possible interpretation of the Ellis-Jaffe sum rule violation
that the strange quark in the polarized proton is remarkably polarized in the
opposite direction of the proton spin, we investigate its implication in the
semi-inclusive $\Lambda$ production in deep inelastic process with the electron
beam unpolarized and proton target polarized longitudinally. As a result, we
find that the measurement of the $\Lambda$ polarization in the process
considered can provide clean information about the strange quark spin
distribution in the proton.
