Wireless Sensor Network (WSN) has a big role in several fields such as military, health and even information technology such as IoT (Internet of Things). Besides having many benefits, WSN has a disadvantage in its application where there is no built-in security system embedded in the sensor device due to limitations possessed by sensor nodes such as memory, processor, and battery. As a result, WSN is vulnerable to attacks, one of the main attacks on WSN is the DoS attack. DoS attacks aim to prevent users legitimate from using resources by reducing existing resources until the network resources are busy, the network becomes slow until finally off. So, we need to detect, mitigate DoS attacks that these attacks can be stopped. In this study, the method of detecting and mitigating DoS attacks uses a signature-based Intrusion Detection System (IDS) by implementing a blocking approach on the attack node by blocking all packets originating from the attacker until the attacker runs out of energy. The blocking approach was successfully implemented on the WSN network when IDS detected a DoS attack. So, the method of blocking approach can be used as a mitigation of DoS attacks by blocking all packets sourced from the attacker.