NFV is an important innovation in networking. It has many advantages such as saving investment cost, optimizing resource consumption, improving operational efficiency and simplifying network service lifecycle management. NFV environments introduce new security challenges and issues since new types of threats and vulnerabilities are inevitably introduced (e.g. security policy and regular compliance failure, vulnerabilities in VNF softwares, malicious insiders, etc.). The impact of these threats can be mitigated by enforcing security policies over deployed network services. In this paper, we introduce an access control as a service model for NFV services. The proposed approach can deploy several kinds of access control model policies (e.g. RBAC, ORBAC, ABAC, etc.) for NFV services and can be easily scaled.