Hitachi Ltd. agreed to pay $19 million to settle U.S. Securities and Exchange Commission charges that the Japanese conglomerate violated U.S. antibribery law through allegedly improper payments tied to South African government contracts to build two power-generation plants.

Hitachi agreed to the settlement without admitting or denying the SEC’s allegations—which claimed Hitachi had violated the U.S. Foreign Corrupt Practices Act by inaccurately recording improper payments made to a front company for South Africa’s ruling political...