This paper deals with the H∞ optimal controller design for a magnetic suspension system model derived in Knospe and Zhu [2011], with added input/output delay. The plant is a fractional order system with time delay i.e., the transfer function of the plant involves infinite dimensional terms including a rational function of √/s and e-hs, where h > 0 represents the delay. The H∞ optimal controller is designed by using the recent formulation given in Ozbay [2012] for the mixed sensitivity minimization problem for unstable infinite dimensional plants with low order weights. The effect of time delay on the achievable performance level is illustrated. © 2013 IFAC.