Due to the advancement of IPTV technologies, Mobile IPTV service is needed to be supported for service and content protection. CAS is generally used in the IPTV service to protect service and content. However, the CAS is not efficient in the Mobile IPTV. The CAS needs too much bandwidth for Service Key update to the each subscriber. Moreover, the CAS is increasing computation burden for the service key refreshment in the key management server when the subscriber frequently changes of the IPTV service group. To solve the problems, we used hierarchical key structure based on pre-shared key that is securely stored into smart card or USIM and do not use the EMM for Service Key update. As a result, the proposed scheme decreases computation burden at the key management server and wireless bandwidth burden in the Mobile IPTV service.