A person who is responsible for a task or situation; the person in charge or supervisor for a site, project, or operation.
イベント当日の責任者は田中さんです。
Mr. Tanaka is the person in charge on the day of the event.
事故が起きた場合は、責任者にすぐ連絡してください。
If an accident occurs, contact the person in charge immediately.
各部署ごとに責任者を決めて報告を受ける。
Assign a person in charge for each department and receive reports from them.