In this study, we aimed to elucidate the mental representation of material categories based on temperature perception. To achieve this, we employed a thermal display to simulate materials based on a thermal model where thermal effusivity is the key thermal property. Participants were prompted to evaluate the perceived materialness of these simulated materials across eight material categories. This approach not only allowed us to observe the relationship between thermal effusivity and the mental representation of material categories, but also to propose a mental representation model represented by a Gaussian function.