Access control in the Internet of Things plays an important role in keeping resources and services secure. As IoT is expanding, centralized access control will not be able to provide service to the entire network in a timely manner. Along with increasing communication overhead, Centralized access control is not suitable for resource-constrained devices. So, in this paper, we have introduced a Decentralized Context-Aware Access Control (DCAAC) mechanism, which reduces communication overhead, provides fast response, and increases battery life by 41.67 \%. The proposed decentralized access control eliminates all intermediary attacks such as Eavesdropping, snooping, interception, and modification attack, which are usually present in a centralized system.