1To assume a new post or position and begin one's duties — commonly used for taking office as president, minister, etc.
彼女は来月、新社長として就任する。
She will take office as the new president next month.
大統領の就任式は毎年多くの注目を集める。
The presidential inauguration ceremony attracts a lot of attention every year.
彼は就任してすぐに新しい方針を打ち出した。
Soon after taking office, he announced a new policy.