Publishing Company
Publisher
noun
If 出版 means publishing, then a company that does said publishing is a publishing company.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own. Will help to know the word 出版 as well, though.
その出版社では、入館の際に身分証明書を提示しなければなりません。
You have to show your ID card to enter the publishing company.