Background: The questionnaires were answered by the patients and their family members who visited the hospitals, the staffs in the hospitals, and the personnels who are involved with clinical trials such as the physicians, pharmacists and nurses for the purpose of surveying the cognition on clinical trial and informed consent. This study was performed in order to provide with the basic information and/or data for supporting to motivate the clinical trials by analyzing the factors affecting the difference of the cognition on each item. Method: The number of whom responded to the questionnaires was 310 in total, which was composed with 137 patients and their family members, 109 staffs in the hospitals, and 64 personnels involved with clinical trials. Result: Most of them were well acquainted with clinical trial, and knew that it is the processes to identify the safety and efficacy with the patients and it has been done in the big hospitals like university hospitals. As the results of surveying the cognition on the processes of clinical trials, most of them were known well but something was not recognized like the patients’ right to see their medical history records. While the expectation which can be obtained by participating in clinical trials was not so big, the biggest one was to get more advantageous benefits (efficacy) from clinical trial. With regard to the cognition on the informed consent, it was well understood its basic concept and procedures. The responders who participated in clinical trials before answered they regard that to conduct the clinical trial is more ethic and the mandatory process to develop the new drugs rather than what those that did not participated in the clinical trials, by 2.0 and 2.7 times, respectively. From the points of general relations considering the participation in clinical trials, the persons with diseases show more experience to participate in it, by 5.8 times, rather than those without diseases, and the persons with medication have 4.8 times more experience in participate in clinical trials than those who do not take the drugs. In addition, the persons who have participated in clinical trials showed more willingness to participate in clinical trials than those who have not participated in it. Conclusion: From the survey results by the questionnaire, considering the current circumstances that the numbers of clinical trials has been rapidly increasing, it was found and is recommended that the persons participating in clinical trials should continuously give the patients and their family members more correct and useful knowledge and information on clinical trials and at the same time that the patients should make their efforts to acquire the adequate information and their duties on clinical trials and make decision of their participation in clinical trials by themselves.