The relationship between sensory processing and ASD-like and associated behaviors in patients with Prader-Willi Syndrome (PWS) remains relatively unexplored. Examining this relationship, 51 adults with PWS were administered the Pervasive Developmental Disorders Autism Society Japan Rating Scale (PARS), Short Sensory Profile (SSP-J), Food-Related Problem Questionnaire (FRPQ), and Aberrant Behavior Checklist (ABC-J). Based on SSP-J "z"-scores, participants were classified into three severity groups. Analysis of variance was performed to compare the behavioral scores of these three groups. Statistically significant group differences were observed in PARS (p = 0.006, [eta][subscript p][superscript 2] = 0.194) and ABC-J (p = 0.006, [eta][subscript p][superscript 2] = 0.193) scores. Our findings suggest that the level of sensory processing may predict ASD-like and aberrant behaviors in adults with PWS, implying the importance of a proper assessment for early intervention.