When someone is having a master degree on something, what would be the best title to be used for him or her?

Answer 1

same if they had no degree at all.

Answer 2

There is no special title given to someone who gets a master's degree. Its not like a Doctorate where people are then given the title Doctor.

Answer 3

In English, there's no special form of address for a person with a master's degree. Just continue to address him or her as Mr., Ms. or whatever he/she prefers. Some college faculty without doctorates prefer to be called Professor, although it's very rare for someone without a doctorate actually to hold that rank.