This study is to identify how infant’s joint attention influences teacher’s efficacy of the infant
class(9-20month) and the development of infant’s vocabulary ability. For this, the study is conducted
with eighty seven infant class teachers and a hundred nine infants from twenty nine daycare centers
in I city of North Jeollaprovince by using MCDI-K, STEBI, and the measuring tool for infant’s
joint-attention.As a result, first, this study reveals that the general teacher’s efficacy of teacher’s
efficacy of the infant class(9-20month) shows a significant positive relations. Second, this study
exposes that both supported joint attention and coordinated joint attention from infants(9-20month)
joint attention show positive relations among the whole vocabulary ability, expression ability, and
understanding vocabulary. Third, this study shows that coordinated joint attention is more influential
than supported joint attention when it comes to teacher’s efficacy of the infant class(9-20month),
infant’s joint attention, and effect of vocabulary ability. In summation, this study explains the
importance of supported joint attention and coordinated joint attention for advancement of infant’s
vocabulary ability. Thus, it is necessary for teacher to provide supported joint attention and
coordinated joint attention through interactions.