Possibly ants have found food in your house. Check where ants are going, and if it is the case, clean up your home to cut off their food supply.
Then you have to use some substance that repells ants. I have found that ants do not like Ajax kitchen cleaner spray, but I am not sure if it is available in your location.
My mom uses grinded cinnamon to repell ants. She says that ants can't stant it.