Every agreement of the wills among two or more persons who make mutual law relation or changes or calls of the existing law relation is named as a contrast in the theory of law. According its characteristics, the law relations may be different - obligatorious, familliarious, hereditorious, administrativ, merchanditorious etc., because of what the contracts as instruments of law regulations of that relationships are published in different law branches, like: familly law, heretige law, administrative law, merchandise law etc. Regarding its theoretical structure and frequent use and meaning in the law practice, the obligatory contracts are separated - those which may make obligatory relationships.The obligatory relationships are law connection among two or more parties from which one of them has the right to ask for, and the other is obligated to give the asked or to do, or not to do, or to bear it. The essence of the obligatory relation is in the right of the creditor to ak from the debtor to fulfille his obligation, which means - basicly - they are in creditor - debtor's relationships. Therefore, the obligatory contracts are double law acts according to which, in the agreement of the wills between two parties, the one part obeys to give something, to do or not to do something, or to bear something in the benefit of the other part, the part which takes that obligation as its right.The agreement of the wills of the contractual parties is one of the four common conditions of the genezes of a contract. It is realized by equality of the different whishes and different aims which the parties like to reach by making an agreement. There are the questions which I am trying to answer in my written text: about law relevant will, the atributes which the will should possesse, the ways of giving the will and, at the end, coordinating the wills of the two parts which goes to make the contact. The coordinating of the wills should be done on a legalized or usual way, frequently or usually by giving an offer from the first part and reaching the offer from the other one. That is the most usual mode of implementation the reunification of the wills between the contractual parts.