A discharge valve system of a scroll compressor comprises: a fixed scroll having a discharge hole and discharge bypass holes; a discharge valve assembly mounted at the fixed scroll, for opening and closing the discharge hole by a pressure difference; and an integral bypass valve assembly mounted at the fixed scroll, for opening and closing the bypass holes and interworking the discharge valve assembly. According to this, a discharge amount of gas is maximized in a low pressure ration driving of the scroll compressor thereby to enhance a discharge efficiency. Also, the number of components is greatly reduced thus to reduce a fabrication cost. Also, the number of assembly processes is greatly reduced thereby to enhance an assembly productivity.