WASHINGTON (AFP) - Sonia Sotomayor was sworn in Saturday as a US Supreme Court justice, becoming the first Hispanic justice on the nations highest bench. Chief Justice John Roberts administered the oath in a televised ceremony held in a conference room at the Supreme Court. The New York-born Sotomayor, whose parents came from the US commonwealth of Puerto Rico, is only the third female justice to sit on the Supreme Court in the courts 220-year history. I, Sonia Sotomayor, do solemnly swear that I will administer justice without respect for persons, and to equal rights to the poor and to the rich, and that I will faithfully and impartially discharge and perform all of the duties incumbent upon me as associate justice of the Supreme Court of the United States, under the constitution and laws of the United States, so help me God, Sotomayor said, repeating Roberts reading of the oath. Roberts earlier held a private swearing-in ceremony for Sotomayor. Sotomayors widowed mother Celina held bible that Sotomayor put her hand on to take the oath, as her younger brother Juan stood by smiling. Sotomayor, 55, who has been a federal judge for 17 years, replaces outgoing justice David Souter, who has been a Supreme Court justice for 19 years. President Barack Obama, who nominated Sotomayor for the job, was not at the event but will hold a White House reception in her honour on Wednesday. Sotomayor was confirmed by a 68-31 margin in the US Senate on Thursday. Hispanics are the fastest-growing US minority group. Most of them are Mexican-American.