This thesis studied procedure of collecting blood as evidence in respect of due process. Blood collection can be presumed to be a method of compulsory extracting blood from a human body, a method of confiscating blood which was collected for treatment and a method of gathering blood which naturally is bleeding out of injure part, etc. Whatever method it is made in, it should be carried out in accordance with due process as the blood collection has a danger of infringing human rights. Blood which is collected without warrant and in violence of due process can’t be used as evidence in principle as it is illegally obtained evidence. But if level of illegality arisen is not as much as the extent of violating practical contents of due process, it can be used as evidence exceptionally.