It is generally accepted that massive galaxies host a supermassive black hole at their center. More interestingly, the mass of these black holes correlate with global properties of their host galaxies, implying that black hole growth and galaxy formation is closely connected. I will review the nature of the black hole -galaxy connection and the current understanding of the black hole-galaxy coevolution. Then, I will describe 3 different methods of determining black hole mass, which is required to understand the physics of active black holes and the coevolution, including our group's recent efforts for reverberation-mapping campaign. Finally I will introduce a few interesting results on the subjects based on our Hubble Space Telescope imaging data and spectroscopic data from the largest ground-based telescopes.