We discuss a dark matter (DM) scenario in an extension of a left-right symmetric model with a gauge-singlet scalar field. The gauge-singlet scalar can automatically become a DM candidate, provided that both P and CP symmetries are only broken spontaneously. Thus no extra discrete symmetries are needed to make the DM candidate stable. We give predictions for direct detection experiments, and show that for some parameter range, the predicted WIMP-nucleon elastic scattering cross section can reach the current experimental upper bound.