Investigators will consecutively enroll subacute (2-6 weeks after stroke onset) patients with first-time, unilateral, ischemic subcortical stroke in the middle cerebral artery territory with mild to moderate hand weakness. All subjects will be randomly allocated to receive daily bihemispheric tDCS (anodal tDCS to ipsilesional M1 and cathodal tDCS to contralesional M1 with 2 mA stimulation for 20 min) or daily sham tDCS (same but stimulation for only 30 seconds) with simultaneous physical/occupational therapy, for total 10 sessions. Changes in upper extremity motor function score (Fugl-Meyer test and Action Research Arm test), corticospinal excitability from the transcranial magnetic stimulation(TMS), and sensorimotor oscillations from the magnetoencephalography (MEG) will be assessed before and after intervention, as well as 3 months after stroke. All stroke patients will receive tDCS and standard medical, rehabilitation treatments in rehabilitation ward.