assistant section manager; assistant department manager
A corporate title for a deputy or assistant manager of a section or department. The exact rank varies by company, but it is typically one step below 部長 (department manager).
He was promoted to assistant department manager this year.
As assistant section manager, I am in charge of preparing for meetings.
部長 is the full department manager, one rank above 出席部長.
課長 is a section manager, often at a similar or slightly lower level than 出席部長, depending on the company structure.
Compound of 出席 (attendance, presence) and 部長 (department manager). The exact origin of the title is uncertain, but it likely refers to a manager who attends meetings or represents the department in the absence of the 部長.