senior executive manager; division general manager
A senior management position in a company, typically the head of a business division or department.
He will take up the post of division general manager from next month.
As the senior executive manager, I will lead the new project.
部長 is a general department manager, while 事業部長 specifically heads a business division, often with broader responsibilities.
本部長 is the head of a headquarters or central office, typically a higher rank than 事業部長.
Compound of 事業 (business, enterprise) + 部長 (department head).