In this paper, we consider a full-duplex amplify-and-forward (AF) relaying with guaranteeing quality of service (QoS). In order to evaluate the QoS guaranteeing ability of FDR, we derive the effective capacity with considering residual self-interference. Based on the analysis and numerical results, it is verified that the stringent QoS constraint degrades effective capacity performance of full-duplex relay (FDR) more severely than that of half-duplex relay. The simulation results also show that the better link quality at S-R link is required in order to guarantee QoS constraint at FDR.