Previous evidence found adolescents with attention-deficit hyperactivity disorder (ADHD) is usually accompanied with inhibitory control deficits. The underlying mechanism might partially due to brain physiology. Therefore, the pilot study aims to explore the relationship between cortical excitability and inhibitory control performance in adolescents with ADHD. The study recruited 7 adolescents with ADHD aged 13-17 years old. All participants were assessed by inhibitory control (stop signal task) and cortical excitability via transcranial magnetic stimulation (TMS). For cortical excitability, Motor evoked potential (MEP) and short intracortical inhibition and facilitation (SICI-ICF) were recorded. Regarding inhibitory control, stop signal reaction time (SSRT), direct error: go trial (DEG) and direct error: stop trial (DES) were recorded. The results found significant correlation between MEP and DEG (r=-0.883, p<0.005), SICI5ms and DEG (r=0.757, p<0.05), ICF15ms and DEG (r=0.847, p<0.05), and ICF15ms and DES (r=0.929, p<0.005). This study found correlation between cortical excitability and inhibitory control performance in adolescents with ADHD. The cortical excitability alteration might partially contribute to the inhibitory control performance in adolescents with ADHD.