The concept of immersion into stories refers to the degree to which readers focus their attention fully on a story and experience the situation in the story like a real world. During such an experience, readers project the representations of the story onto the text itself. Although researchers have investigated whether reading narrative fiction is positively associated with social ability, empirical studies do not provide consistent results. We hypothesized that individual differences in story immersion can influence the relationship between reading stories and mindreading. In Study 1 (with adults) and Study 2 (with children), we measured participants’ exposure to stories, their proneness to story immersion, and mindreading. In contrast to previous studies, we did not find significant correlation between exposure to stories and mindreading. Story exposure,however, was associated with the story immersion in both adults and children. Furthermore, the result of Study 1 showed significant correlation between story immersion and mindreading. These results suggest an important role for story immersion on the enhancement of mindreading. This possibility is discussed in light of the methodology used to measure story immersion and developmental changes in reading experience.