Refers to the publishing company or entity that produces a book, magazine, or other publication.
この本の出版元はどこですか。
Who is the publisher of this book?
出版元 and 出版社 both mean 'publisher,' but 出版元 is a slightly more formal/technical term often seen in credits, while 出版社 is the everyday word for the company itself.
Compound of 出版 (shuppan, 'publishing') and 元 (moto, 'origin' or 'source'), literally 'publishing source'.