This paper presents a study on comparison between integer order PID (IOPID) and fractional order PID (FOPID) control of a magnetic bearing system. First, a magnetic levitation system model is derived. Genetic algorithm is used for the controller design to compensate derived model. Different fitness functions are used to determine controller parameters. System responses are compared for two controllers. Also, controller performances are tested both when the operation point is varied and controller parameters are changed. Moreover, a comparison between IOPID and FOPID is done.