Apple does not make any carrying cases for their laptops. There are many companies though, that make carrying cases specifically for Apple's line of laptops. Do a forum search for "macbook carrying case" and you'll find plenty of existing threads with recommendations on different vendors and styles of cases.
I have "Brenthaven edge I" for my MacBook and absolutely love it. I don't carry power charger/adatper around so even though it snugly fits my MacBook only, I feel like it is very well protected.