The 3rd century crisis started a process of collapse that was felt in all areas of Roman Empire. The Senate, the source of legitimacy of the state, was also affected by this collapse process. Simultaneously, each military unit, without seeking the Approval of Senate, declared its commander as emperor in different regions of the Empire. The emperors tried to get the support of the army instead of getting the approval of the Senate. The rule of Maximiaus Thrax, who came to power with the support of his soldiers in 235, was the first stage that broke the positive relationship between the senate and the emperor. During the Gallienus’ rule, the reduction of the military and administrative powers of senate caused it to remain a symbolic institution. The instability caused by military anacrhy showed that in 275, the senate should again be an authority on the election of emperor. With the election of the new emperor, senate sovereginty was established for a short time. However this emperor which legitimizde by the senate was also removed from power by a military coup. The aim of this study is to reveal the relationship between the emperor who constantly increased his power throughout the crisis and the senate.