The main aim of thiis proposal is to investigate magnetic properties of MoO2. This system is one of molybdenium oxides, MoOx, which is widely applied for industrial purposes. The MoO2 shows the metallic behavior. The room-temeprature ferromagnetism has been reported in thin films. Due to those phenomena, MoO2 can be regarded as a good candidate for spintronics devices, photovoltanic power generation materials and high-capacitor of Li ions as batteries. Although it is well known that this system shows the metallic behavior, its mangeitc properties are still less studied because of small magnetic moments in the metallic state. We propose to investigate those unclear magnetic properties by muSR and try to reveal the predicted room-temperature ferromagnetism and its magetic ground state.