Using the intelligence evidence, the US with the UK as its main backup, had convinced UN Security Council's member states to decide on sending disarmament military forces to Iraq. Aside from the political reason which the two states might have as their real vest interest in Iraq, it is interesting to explore the condition of how could such proposed sophisticated intelligence might turn so wrong. There must be factors which caused that intelligence failure. Based on the thought that in principle intelligence product is heavily depended on input data and its analysis, the real failure factors of intelligence in assessing the real condition of Iraq's weapons of mass destruction program is sought through examination on data collection and its analytical process.As the result it found that unavailability of information as the most common problem involving restrictions on the circulation of sensitive in-formation was one of the intelligence failure factors. The other factor is the systemic, systematic, idiosyncratic and communicative variables within analytical process employed by the intelligence community. Unavailability of information has been exacerbated by counterintelligence (deception and denial attempts) of Iraqi security apparatus and the absence of an intelligence collection in Baghdad with the capability to penetrate government, military and scientific establishment in the capital. Overestimation of Saddam Hussein's warfare capability is caused by mirror imaging of western method he would choose in nuclear and weaponry research, while conventional wisdom is indicated being use as the analytical bases and there were also subordination of intelligence to policy which not because of pressure but rather the insufficient evidence analyst could get.