This study validified the Behavior Development Screening for Toddlers-Questionnaire/Teachers (BeDevel-Q/T), an autism spectrum disorder (ASD) screening instrument. This assessment serves the purpose of teacher reports for early screening of ASD on infants aged 9-47 months. Pilot tests were conducted on a total of 217 people(N=179 typical development, N=32 ASD, n=6+DD). A total of 1,936 participants were tested N = 1,833 typical development, N = 62 ASD, N = 41 developmentally delayed). The results showed a line between age ranges of 9-11 months, 12-23 months, 24-35 months and 36-47 months. Each age ranges consisted of 7-27 questionnaires and 3 subfactors. BeDevel-Q/T validity was tested by the general developmental criterion of BeDevel-Q/T, M-CHAT, Autism items from BITSEA and sociability items from K-DST. M-CHAT, Autism items from BITSEA and sociability items from K-DST were also employed and correlation analysis was performed and general differentiation factors between ASD, developmental delayed, and normal groups were also considered. Results showed a reasonable level of acceptability. BeDevel-Q/T showed high sensitivity (50.0-85.0%), specificity (59.60-84.8%), high internal consistency (Cronbach's α=0.72-76) as well as high test-retest reliability (r=0.79-94). Our results suggest that BeDevel-Q/T might work as a useful short form screener for early identiﬁcation of ASD in primary care settings.