In terms of bills of exchange, which are credit, collateral and payment instruments, it is possible to conclude a circulation contract through a representative. While this opportunity makes life easier, on the other hand, it causes various legal problems such as unauthorized representation and abuse of representation power. In order to be able to characterize these two situations, which are frequently encountered in practice, first of all, it is necessary to examine the representation institution in law of commercial papers. Subsequently, the cases of unauthorized representation in bills of exchange and abuse of representation power, the fate of the representative's signing with "past date" regarding the period of his/her unauthorized period, and the responsibility of the merchant in the context of the liability of the assistant's act in cases where the representative is an assistant merchant even if he/she is unauthorized are among the problems that will be examined in the study.