IPTV is well known services of TPS (Triple play service). Since TPS supplies the bundle service, service providers can supply low-priced services for their subscribers. To supply high quality contents stably, it is an essential requirement to make payment for the services. According to the type of services, either CAS or DRM is used to protect the pay-contents service. Also IPTV uses or will use these security systems to protect the service. In this paper, we will describe security problems when a IPTV service provider chooses either CAS or DRM, and then propose a new security system to solve the problems.