Throughout our lifetime, we are constantly approaching or avoiding situations such as places associated with positive or negative outcomes, respectively. However, individuals are often confronted to a relative choice between two situations holding negative outcomes of different intensities, leading them to choose the least bad option. While extensive work focused on appetitive relative value coding, surprisingly little is known about the neural processes underlying relative value coding in an aversive context. To understand how animals make relative aversive choices, it is crucial to identify the brain circuits and mechanisms involved in learning relative (better or worse) aversive value. Here, by designing a newly-developed conditioned place aversive task, we found that mice can successfully perform both relative and absolute aversive value-based choices, yet they exhibit distinct behavioral strategies to select the best of two options. Using a combination of pharmaco/optogenetics and in vivo recording of neuronal activity in behaving mice, our data revealed that the paraventricular thalamus (PVT), a region that can integrate positive and negative emotional states to guide behavior under motivational conflict, is critical to learn relative aversive value.