Usually the Chief Justice, but any person with the legal power to administer oaths may do so. Calvin Coolidge, visiting his parents in Vermont when President Harding died, was sworn in by his father, a local Justice of the Peace. Only seven other times in US history has the oath of office been administered by someone besides the Chief Justice of the US.
The president swears that he will faithfully execute his office as president.
inauguration
inauguration
Yes, when he is sworn into office he swears to uphold the Constitution.
inauguration
Honor
The ceremony is called the inauguration.
He says, "I do solemnly swear (or affirm) that I will faithfully execute the Office of President of the United States, and will to the best of my Ability, preserve, protect and defend the Constitution of the United States."
When the President of the United States is sworn into office, he swears to preserve, protect, and defend the Constitution by taking the following oath of office : "I do solemnly swear (or affirm) that I will faithfully execute the office of President of the United States, and will to the best of my ability, preserve, protect, and defend the Constitution of the United States."
Inagural Address - this is the speech the President gives the country at the inauguration ceremony, right after he swears his oath and is declared "in office" and the President of the United States.
The Vice President of the United States swears in new senators, the speaker of the house does not. speaker of the house
Traditionally, the Chief Justice of the United States administers the Oath of Office to the president-elect. For Barack Obama's inauguration, Chief Justice John Roberts administered the oath of office to the president-elect, Barack Obama.