Although a number of case with adult ADHD has been increasing in Japan , helpful diagnostic method of it has yet not existed. Recently, effective and supportive findings on cerebral SPECT with statistical methods have been fund in cases with Japanese adult ADHD. During 2 years, 15 cases with Japanese ADHD diagnosed by DSM-5 were examined with IMP-SPECT using statistical methods. ROIs were placed on anterior and posterior lobe of cerebellum on IMP SPEC with vbSEE level 2 software and other regions with that level 5 software. Significant decrease was observed on cerebellum in 8 cases (bilateral in 6 cases, unilateral in 2 cases), upper posterior lobe, thalamus in 4 cases, middle posterior lobe, lower posterior lobe, pons in 2 cases, cuneus, lingualis gyrus in 1 case. In total 15 cases, there were significant decrease in posterior lobe of cerebellum compared with anterior lobe (left side: p=2.24E-05, right side: p=2.63E-05). Those results were in accordance with those of studies with SPECT with statistical methods. Hypoperfusion on posterior lobe of cerebellum on SPECT with statistical methods might facilitate the diagnosis of adult ADHD in Japan.