noun
An official document granting permission to do something, such as a driver's license, building permit, or entry pass.
運転するには許可証が必要です。
You need a license to drive.
工事を始める前に許可証を取得してください。
Please obtain a permit before starting construction.
許可 is the abstract permission or approval, while 許可証 is the physical document or certificate proving that permission.
Compound of 許可 (permission) and 証 (certificate, proof).