Nowadays, argument of observing woman right and equality of observation between genders is one of problems which draw international assembly attention. Witness argument is important problem in this direction. In all countries, although, witness is one of reason of claim proof and gender do not have effect on its validity in some countries. There are some differences between witness validity of women and men in law regulation of Iran, that writer investigates view which consider the difference of men and women's witness as deficient of woman value ,along with emphasis that witness is duty not right. Also, he has investigated juridical principles of such regulations. It seems that it is necessary to investigate the woman witness issue and such issue. According to draft of many propounded issues in Islamic Republic of Iran throughout issues which are related to human right and existing doubt to their juridical principle. In this paper, the subject has been investigated by using documentary method. Finally, it admitted that witness chapter does not have relation to wisdom and rationalities, but perceptible is discussed here. However, inequality of woman witness value to man is not a reason of inequality of physical and intellectual ability of woman. But it is a strategy on behalf of religious law for exemption from duty, not depriving of right.