Yes, Saudi Arabia is an Arab country.

The Kingdom of Saudi Arabia (Arabic: ?, English: Kingdom of Saudi Arabia) is located on the Arabian Peninsula in southwest Asia, bordering the Persian Gulf to the east and the Red Sea to the west. It is a country with Jordan, Iraq, Kuwait, and the United Arab Emirates. The emirate borders Oman, Yemen and other countries. Saudi Arabia is a veritable "petroleum kingdom" with its oil reserves and production ranking first in the world, making it one of the richest countries in the world.