public institution; public organization; official body
Refers to government agencies, public offices, or officially recognized bodies that serve public functions.
This certificate was issued by a public institution.
I recommend consulting an official body.
公共機関 emphasizes public utility or service (e.g., transportation), while 公的機関 focuses on the official or governmental nature of the organization.
政府機関 specifically refers to government agencies, whereas 公的機関 can include quasi-governmental or officially recognized bodies.
Compound of 公的 (public, official) and 機関 (organization, institution).