We investigated the feasibility of our novel evaluation system for use with children with autism spectrum disorders (ASD). We prepared the experimental setting with two humanoid robots in reference to the birthday party scene in the Autism Diagnostic Observational Schedule (ADOS). We assessed the relationship between social communication ability measured in the ADOS condition (i.e., with a human clinician) and in a robotic condition for children with ASD. There were significant correlations between the social communication scores in the gold-standard ADOS condition and the robotic condition for children with ASD. The current work provides support for a unique application of a robotic system (i.e., two robot-mediated interaction) to evaluate the severity of autistic traits for children with ASD.