Totally normal! :) It's called separation anxiety, and usually hits right around this age.
If you ask the folks at daycare, they'll probably tell you he fusses for a short while after you leave, and then goes & plays, or watches the other kids, etc.
Here's something you can do at home. Start off by playing peek a boo. First in the same room, then get up & go to a doorway so you can hide around the corner. (If he starts to follow you, go faster!) Keep showing him that even though you are "gone" you always come back.
If you have someone around who can keep an eye on him for a minute or two, you can also go out one door, and wait a minute, then come in a different door. (This can include going outside.)
Again, it shows him that you DO come back. He's learning about object permanence (I think I spelled it right.) Meaning objects can reappear, from various places, even when you thought they were gone. And it includes people.
Playing some of this type of game hiding toys & helping to find them, etc, should all help.
But mostly, just time will help. He'll figure it out pretty soon.
Just wait! The terrible 2's & 3's are coming! And you get to (sometimes) go thru it again! (Luckily, for a shorter amount of time.)
Good luck!