Provided are an electrostatic discharge (ESD) protection device having a high-resistance region and a method of forming the same. The device includes a well on a substrate. A first impurity region is formed on the well and connected to an input/output pad. A second impurity region is formed on the well, spaced apart from the first impurity region, and connected to a ground (Vss). A third impurity region is formed on the well, spaced apart from the first impurity region, and connected to the ground (Vss). An isolation layer is formed between the first impurity region and the second impurity region. A high-resistance region, which directly contacts the first impurity region and the well and has a resistance higher than the first impurity region, is formed between the first impurity region and the isolation layer. The well and the third impurity region include first conductive type impurities. The first impurity region and the second impurity region include second conductive type impurities different from the first conductive type impurities.