Rather than merely a reflection of ethics, the journalistic norm is an out-come of social construction. American journalism has been spread worldwide, and its core concepts--such as "objectivity," "social responsibility," and so forth--result from the actions of agents in the journalistic field that respond to the political and economic needs. In Taiwan, this set of journalistic norms has been translated and re-defined in accordance with the change of political and economic structures. This paper aims to analyze the development of Taiwanese journalistic norms throughout the three periods since the end of the World War Ⅱ, including (1) The formation of "client media's responsibility theory" between the 1950s and 1970s; (2) The emergence of "political dissidents' media ethics" which challenged the former in the 1980s; and (3) The rise and suppression of the "autonomous journalistic norms movement" from the mid 1990s to the present.