noun
supplier company; supplying firm
Refers to a company that delivers or supplies goods, often in a business or procurement context.
新しい納入会社と契約を結んだ。
We signed a contract with a new supplier company.
仕入れ先 is a more general term for a supplier or vendor, while 納入会社 specifically emphasizes the company as a delivering entity.
Compound of 納入 (delivery, payment) and 会社 (company).