Questionnaire is one of the most popular statistical data collection tools therefore its design has a profound impact on quality of collected data. Applying principles like: avoiding ambiguous, complicated and general questions as well as choosing appropriate appearance and layout can improve questionnaire design quality. Assessment of these principles, particularly from content view point, may not be possible by looking at questionnaire only, so questionnaire evaluation before main survey implementation is suggested. Different methods have been introduced on questionnaire evaluation.  This article presents "interviewer debriefing" method which is used in questionnaire evaluation of "Survey on producer price indices and production quantity on mining section-2009", Statistical Center of Iran, and the results has been analyzed. The results show that "interviewer debriefing" is a suitable method in questionnaire evaluation of this survey.  In this article some recommendations to improve questionnaire design and filling out procedure are given to interviewers.