Is it better for my baby (5 month old) to sleep on his tummy?

Has he learnt how to roll over yet? I make sure my baby sleeps on her back, but that's because she's only 2 months old. It's not recommended for infants to sleep on their tummies if they have not yet learnt how to roll over as they might not be able to turn over in time if their air passage is obstructed by the bedding. If you would like him to sleep on his tummy nevertheless, do check on him often, just in case. Also, try to keep the bed clear of any soft material which may cause suffocation.