The modulation of Arctic Oscillation (AO) by Madden-Julian Oscillation (MJO) is suggested. MJO index, which is centered near southwestern Asian Ocean, and AO are highly correlated in intraseansonal timescale especially during March-April-May in northern hemisphere. As anomalous divergent forcing is exerted in tropics and moving eastward from Indian Ocean to western Pacific, the barotropic reponse of midlatitude is changing to NAO and PNA-like phase alternately. This modulation leads to in-phase relationship between MJO and AO.