The gravitational wave astronomy has just begun.
Through the discoveries made by the network of the LIGO and Virgo gravitational wave detectors, we are enjoying the power of the new way of studying the universe. The power is obtained by sophisticated gravitational wave data analysis techniques, which enable us to look deep into the noisy detector data streams. Here in this talk, I would like to summarize the current findings out of the discoveries, and then review data analysis techniques utilized in the field. I also report on the status of the KAGRA gravitational wave detector built in Gifu prefecture, Japan and its future plan, as well as the data analysis activities for the KAGRA project.