In the principle 23 of suggestive legal article (1386) of the Protection of Family, the husband commitment, for dealing justly between his wives, is defined as one of the conditions of his next permanent marriage. Indeed, it comes from a Quranic verse, "if you fear that you May not be able to deal justly with them (wives) then only marry one free woman" (AI-Nisa', 3), which declare the possibility of polygymy and also limit its quantity. In addition, the justice is the most supreme human accomplishment that is one of the ethical goals of social relationship. In this way, it has been recognized as a rule in marital issues, such as cost of living, and cohabitative time. However, love and emotion like other psychological subjects can't be controlled by human, completely. So, dealing the justice in emotions, which means an exact dividing, is a very hard obligation. Nevertheless, Islamic human studies that understand the sprite as a greater capacity define the possibility of devoting the emotions to several wives, justly. Therefore, dealing of this marital justice is an ethical endeavor, which is implemented by husband, for proving his lovely affection to the wives. So, this kind of commitment is proposed, based on the ethical guarantee.