Since the first convincing detection of planets orbiting stars other than the Sun, or exoplanets, in 1995, our knowledge on exoplanets is extremely expanded both in quantity and quality; approximately 4000 exoplanets and new kinds of exoplanets unknown in our solar system are discovered. Various exoplanet detection methods are already successful including direct detention. Most recent detection of earth-like planets around nearby M-stars such as Proxima b and Trappist-1 b-g will be a tip of iceberg; there will be plenty of them around nearby M stars and they are the best targets for the life-signature finding on exoplanets in the next 10-20 years.