How public interests are reflected in media merger regulation? How in a specific case, various aspects of public interests are addressed in the political process? Taking as example the famous News Corp/BSkyB merger case, this paper examines how UK's media merger regulatory regime really works. Having analyzed the political process in this case, the author makes clear that in UK regulations, media mergers are considered as something to do with special public interests, which are not only economic-such as market competition, but also socio-political- such as democratic diversity and social responsibilities.As laid out in the regulatory framework, the News Corp/BskyB merger should go through the public interests test, despites the alliance between Conservative Party and Rupert Murdock. Activists who argued against the case were based more on plurality-related values in the beginning, but then concerned more with values of social responsibilities (”fit and proper”) after the phone hacking scandal broke out. In conclusion, the author suggests that public interests can only be safeguarded by a healthy legal framework, and strengthened by caring social activists.