Yes. If your group is designed for a specific set of people (and not the general public) and you want to control membership, then you should choose to make your group restricted, which means you approve all memberships.

You’ll need to send invitations to the people who might want to join.

Here’s how to make your group restricted:

1. From the list on the left, click Management. This link only appears if you’re the owner of the group or a moderator with the appropriate privileges.
2. Under "Group Settings", click "Membership".
3. Click Edit next to "Membership Type & Welcome Message".
4. Choose "Restricted" next to "Membership Type".
5. Click Save Changes.