There was a first direct detection of gravitational waves last year. This informed us of the dawn of the era of gravitational wave physics. The perspective of future observation became definitely brighter than before. Although the well-known guaranteed source of gravitational waves, binary neutron star merger, has not been detected, it will be soon or later detected as the world-wide network of gravitational wave detection develops. Furthermore, the possibility of early realization of future space mission might be increasing. I’d like to give some perspective on gravitational physics and discuss the challenging issues that requires theoretical study.