minister (of government); noble
「大臣」 has another reading with different meanings.
cabinet minister
彼は財務大臣に任命されたんだ。
He was appointed finance minister.
新しい大臣が就任したらしいよ。
A new minister seems to have taken office.
大臣としての責任は重いと思う。
I think the responsibility as minister is heavy.