Ben Affleck ''couldn't be happier'' with his baby son.

The 39-year-old actor and wife Jennifer Garner welcomed little Samuel into the world on February 27 and he is enjoying taking time off to be with his family, which also includes daughters Violet, six, and three-year-old Seraphina.

A source told People magazine: ''He couldn't be happier. He loves his wife. He loves his family and he's proud - he's legitimately proud - you can just see it.

''He's gets to spend a lot of time with his family and the idea that they have three kids right now is something that makes them both feel really good.''

Jennifer - who married Ben in June 2005 - is ''feeling good'' after the birth and the couple's daughters are smitten with their baby brother.

The source added: ''Jen is feeling good. She is such a natural mother. She's so thrilled to have a little boy, and the girls already love him so much.''

During her pregnancy, Jennifer, 39, revealed Ben ''wasn't sure'' about having a son.

She said: ''I would have thought [he wanted a boy]. At first I think I really thought so. And then he kind of said, 'Well, we have girls. We know how to do girls. My girls love me. I'm the big guy in the house.' So, now I'm not sure.''