Research regarding digital forensic technologies has become more active with the recent increases in illegal accesses to computer systems. Digital evidence is easy to modify and erase. In order to collect the evidence with integrity and fidelity, digital evidence collecting system which is set in the target system in advance is proposed to collect digital evidence for purpose. And the security of forensic mechanisms themselves is another serious problem. Based on the analysis of relative researches, secure area is proposed to protect forensic mechanisms from attacking.