Rzadziej -secretarial office np: Management Board Secretarial Office.

Czasem po prostu- ADMINISTRATION (administrative office)

RACZEJ NIE- SECRETARIAT
The secretariat of an organization is the department that fulfils its central administrative or general secretary duties. The term is especially associated with governments and intergovernmental organizations such as the United Nations, although some non-governmental organizations (for example, the International Organization for Standardization[1][2]) also refer to their administrative department as their secretariat. The building or office complex that houses such a department may also be referred to as its secretariat or secretariat building

COMPANY SECRETARIAL DEPARTMENT
While many corporate secretarial departments have staff to complete these tasks, they may lack a centrally managed system or process-driven approach to...
http://www.pangea3.com/solutions/risk-management/corporate-g...

POR też: Corporate secretarial department/ office

Mozna też kombinowac opisowo ( department for- zależnie od szerszego kontekstu), ale chyba nie ma takiej potrzeby.