The present invention relates to a power transmission device of the clutchless compressor, which includes: a pulley; a hub disposed in one side face of the pulley and connected to a driving shaft of a compressor; a drive-side connection member including a connection portion detachably connected to one side face of the pulley and a breaking portion connected to the connection portion and broken when a torque above a preset value is generated in the compressor; and a driven-side connection member connected to one side face of the hub and is connected to the breaking portion and including a plastic deformation portion outside the driven-side connection member so that the driven-side connection member is plastic deformed or is broken due to plastic deformation if a rotational shock is applied from the connection portion to a remaining breaking member remaining even after the breaking portion is broken.