Designing a flexible transparent electronic device with biological functions is of great interest for the future wearable integrated artificial intelligence equipment. Nociceptor is a vitally important receptor of sensory neuron, which is responsible for providing a warning signal by recognizing noxious stimuli to reduce potential physical injury. Here, a flexible transparent artificial nociceptor device is demonstrated to simulate the biological nociceptor functions based on the indium tin oxide (ITO) memristor, which exhibits forming-free and reproducible threshold resistive switching behaviors. This structurally simple memristor can imitate the key features of biological nociceptor, including “threshold,” “relaxation,” and “no adaptation” behaviors and sensitization phenomena of hyperalgesia and allodynia upon external stimuli. Finally, an alarm system is built to demonstrate the simplicity and feasibility of this artificial nociceptor for future neuromorphic systems. These results indicate a potential application of the ITO memristor in the future flexible invisible neuromorphic cognitive platform.