Transcranial alternating current stimulation (tACS) is a noninvasive method of brain stimulation that can modulate oscillatory brain activity in the cortical region. By applying alternating current through two electrodes attached to a subject’s head, it is possible to entrain the oscillation of the cortex directly under one electrode to a specific frequency. In this review, we described our recent findings that tACS to the primary motor cortex and cerebellar hemisphere improves motor performance. We also described the effect of tACS on the supplementary motor cortex to modulate the maintenance and updating of motor plans in a bimanual motor task. These recent findings show that individualized tACS interventions can be tailored by selecting the stimulation area and frequency depending on the subject’s performance level and exercise task. By further investigating the effects of tACS on motor performance, we believe that tACS can be applied to rehabilitation.