Inhibition of Return' is the inhibition mechanism that is nearly to becoming automatic process and it is essential in effective visual search. The aim of this study is to clarify whether there are subgroups showing inhibition of return deficit in ADHD group or not, and to examine the features of ihnibition of return deficit in ADHD group. As a results, 10 children among 24 ADHD group that were consulted psychological testing under impression of ADHD didn't show inhibition of return in condition of 1000ms SOA(Stimulus Onset Asynchony). In group comparison test, there were no significant group differences on IQ and age variables between groups, but there were significant group differences in reaction time variance(in CPT). In other variables of CPR the performance(ommission error, commission error, reaction time), 14 children who showed 'inhibition of return' were superior to 10 children who didn't show 'inhibition of return'. The result of this study indicated that there exist subgroups in ADHD and that the inhibition of return mechanism will be the indicator to discriminate the child with basic attention deficit from the child with temporarily attentiond problem due to emotional problem.