Is their any health benefit of wearing undergarment.?

Not really. There may be hygiene issues! one may use underwear to wick perspiration and stay dry and to give support to the genitals (if male). Undergarments may prevent (or cause) chaffing and rashes. Though, no undergarment my provide better circulation, increase sperm count and prevent yeast and other problems. It really comes down to personal preference. To wear or not to wear, that is the question?