This thesis attempts to discuss the rule of contra between the elements in the contract of sale and its relation with the object of justice between the two contractual parties. The object of justice is an absoulute and legally confirmed object through plenty of proofs derived from the noble book and the prestige Sunnah. This justice in sale is achieved by making equality between the two contractual parties as much as possible, if absolute equality is not possible, we try to bring an approximate equality between them, the best way to ascertain the presence of equality between the contractual parties can be done by the rule of the contra between the elements, wich indicates that everything exchanged by the buyer must correspond in value to the merchandise offered by the seller. When there is correspondence between the exchanged merchandaise, than justice is ascertained in the contract. However, if there is any element in the contract for wich there is no correspondence, then that would indicate the presence of excess for one of the two contractual parties. This excess will affect the foundation of justice between the two contractual parties. Most often it will influence the validity of the sale agreement. In some ways this excess could either be usury or a condition, which consists of additional benefit from one of the two contractual parties over the other, otherwise, it could be an instance of fraud, and the like, likewise the researcher attempts to apply this rule over some of the fiqh issues as mentioned In the Fiqh heritage books, and then to apply it to some contemporary issues which have generate great discussion, for instance: insurance, Sale by installments, and Tawarruq. By this, the study attempts to demonstrate the viability of this rule as it is to be applied on existenting Fiqh issues, in addition to modern ones.