I don't want to lose weight as I am underweight. Been skipping, can it helps to lose belly fat eventually?

Yes. All forms exercise can help you eventually lose belly fat, however if you are underwt I can't imagine that you have much belly fat! I hope you are not trying to look like the thin models in pictures that have no fat at all! Sometimes there's a little skin on the belly and when we sit down it bulges and we mistake that for fat! It's skin! Just follow a sensible balanced diet and exercise! :)