noun
Typically refers to the chief of staff of the US president, but can be used for other high-level executive assistants in government or large organizations.
See also: 大統領首席補佐官 (だいとうりょうしゅせきほさかん)
大統領首席補佐官はホワイトハウスの運営を統括する。
The President's chief of staff oversees the operations of the White House.
彼は知事の首席補佐官に任命された。
He was appointed chief of staff to the governor.