This study aimed to clarify factors related to difficulties in responding to "yes/no" questions (Y/N-Qs) among 52 children with autism spectrum disorder (ASD), 41 boys and 11 girls aged between 3:5-16:0 years. Participants completed the Tanaka-Binet Intelligence Scale V, the Picture Vocabulary Test: Revised (PVT-R), and the Pervasive Developmental Disorder-Autism Society Japan Rating Scale (PARS). A "yes/no" test, developed for this study, included two types of task: a naming true/false task and a request-intention task. For the naming true/false task, clear "yes/no" responses accounted for 60% of responses among preschool children and more than 90% of responses among school-aged children in the normal IQ and mildly cognitively-impaired groups. In contrast, clear "yes/no" responses accounted for less than 30% of responses in the moderately cognitively-impaired group, and less than 1% in the severely cognitively-impaired group. For the request-intention task, clear "yes/no" responses were higher than for naming true/false tasks. Multiple logistic regression analysis indicated that scores of PARS, estimated mental age, vocabulary age according to the PVT-R, and IQ are associated with clear yes/no responses. These findings appear to indicate that ability or inability to respond to Y/N-Qs follows a developmental pattern in children with ASD. (Contains 6 tables and 4 figures.)