The aim of the study was to validate the Polish version of the Perceptions of Inclusion Questionnaire (PIQ) for the first time. The analysis included not only pupils, parents/legal guardians, and teachers but also physical education teachers, which is an innovative solution proposed by the authors. The sample consisted of 448 respondents. Confirmatory factor analysis showed that the tested model corresponding to the construct proposed by the PIQ authors did not have good fit indicators (χ2/df = 7.73; CFI = 0.855; SRMR = 0.103; RMSEA = 0.123). The three-factor structure of the questionnaire was confirmed by the eigenvalues obtained for each extracted factor based on the Kaiser criterion and the scree plot based on the Cattella criterion. All three factors showed satisfactory levels of reliability (Cronbach’s alpha > 0.7). The conditions of convergent and discriminant validity for the construct were confirmed. However, Horn’s parallel analysis showed that the optimal number of factors is 4. Therefore, the research presented here should constitute a starting point for further analyses. It is recommended that research teams should conduct further scientific exploration of the PIQ tool in four perspectives, i.e., including PE teachers’ opinions.