Explanation:

An oath of office is an oath or affirmation a person takes before assuming the duties of an office, usually a position in government or within a religious body, although such oaths are sometimes required of officers of other organizations. Such oaths are often required by the laws of the state, religious body, or other organization before the person may actually exercise the powers of the office or organization. It may be administered at an inauguration, coronation, enthronement, or other ceremony connected with the taking up of office itself, or it may be administered privately. In some cases it may be administered privately and then repeated during a public ceremony.

Now, in India Article 75(4) of the Constitution in the Third Schedule provides that before a Minister enters upon his office, the President shall administer to him the oaths of office and of secrecy.