Purpose: Relatively few ADHD drugs are available in Japan, but psychotropics are often used for the comorbidity of ADHD. We aimed to compare juvenile and adult patients in terms of drugs used for ADHD. Methods: We retrospectively surveyed the circumstances of prescriptions for atomoxetine and concurrent medications for ADHD patients (36 men, 39 women) using electronic medical records from a single-department psychiatric hospital in rural Japan. Mean dosage, period and rate of administration continuation, side effects, reasons for cessation, comorbid diagnoses, and use of concurrent medication were statistically compared between juvenile (<18 years old) and adult (≥18 years old) groups using the t-test and χ2 test. Results: Continuation rate was significantly higher in the adult group (43.5%) than in the juvenile group (20.7%; p=0.043). In the juvenile group, 65.5% received monotherapy and 34.5% received combination therapy, compared to monotherapy for 37.0% and combination therapy for 63.0% in the adult group. Combination therapy was significantly more frequent in the adult group (p=0.015). Discussion: These findings were attributed to differences in motivations for medical treatment and care-receiving patterns between groups. Since juvenile people often start treatment for ADHD as a primary condition, rather than as a comorbidity, concomitant medications are less frequent. Juvenile patients tend to drop out because of poor subjective symptoms. Among adults, treatment for ADHD often begins as treatment of comorbidity, so concomitant medications and maintenance therapy are more frequent than among juvenile patients.