Aim: The aim of this study was to verify the stress distribution associated with the thickness and elastic modulus of the palatal mucosa by three-dimensional finite element models of a dentulous subject and a pseudopalatal plate at pain onset after loading with a clenching force. Materials and methods: The subject was a 35-year-old man with a dentulous jaw. Fourteen measurement sites were designated on the subject's palatal mucosa, and the mucosal thickness and load amount at pain onset were measured at each site with an ultrasonic thickness gauge and a strain gauge. These data were used to calculate the elastic modulus. Next, a pseudopalatal plate was created from scanning resin and photographed using cone-beam computed tomography. Three-dimensional finite element analysis (FEA) software was used to construct the pseudopalatal plate part. In addition, measurements of the actual mucosal thickness were added as elements to the mucosal surface of the pseudopalatal plate part. It was configured with the elastic modulus values of the palatal mucosa part. The load was the clenching force at the onset of pain (111 N cm) based on a previous study. Results: The conventional and optimized models showed greatly different stress distributions. In addition, thick areas of the palatal mucosa were more susceptible to influence from the elastic modulus, while in the thin areas, stress generation was not related to the elastic modulus. Conclusion: Differences in thickness have a greater impact on stress distribution than differences in elastic modulus. Thus, the results demonstrated the importance of building a model based on actual measurements of the thickness of a subject's palatal mucosa.