An apparatus for preventing vacuum of a scroll compressor is provided. The apparatus includes a fixed scroll having a bypass hole, through which a suction chamber of a casing is connected to a discharge chamber of the casing; a valve block having an inner channel, through which the bypass hole of the fixed scroll is connected to the discharge chamber of the casing, and fixedly installed at the fixed scroll; and a valve member disposed between the bypass hole of the fixed scroll and the inner channel of the valve block. Since the apparatus is assembled at an outer periphery of the fixed scroll, a processing error of the fixed scroll is prevented, thereby reducing production costs. Also, since foreign materials generated when a refrigerant channel is processed do not remain in a valve hole, the valve member is prevented from being mal-operated, productivity is enhanced, and fabrication costs reduced.