A scroll compressor, comprising: a casing; a discharge cover, the discharge cover dividing an inner space of the casing into a suction space and a discharge space; a main frame, the main frame being spaced apart from the discharge cover; a first scroll supported by the main frame, the first scroll being configured to perform an orbital motion with respect to a rotational shaft in operation; a second scroll (140; 340) forming a suction chamber, an intermediate pressure chamber, and a discharge chamber together with the first scroll, the second scroll (140; 340) being movable with respect to the first scroll; a back pressure plate (150; 250; 350) coupled to the second scroll (140; 340), the back pressure plate (150; 250; 350) comprising a cavity with which the intermediate pressure chamber of the second scroll (140; 340) communicates, a lower surface of the back pressure plate (150; 250; 350) facing an upper surface of the second scroll (140; 340); and a floating plate movably coupled to the back pressure plate (150; 250; 350) so as to seal an upper portion of the cavity, wherein the back pressure plate (150; 250; 350) comprises: a supporting plate (152; 352), the supporting plate (152; 352) contacting an upper surface of the second scroll (140; 340); a first ring-shaped wall (158; 358) formed to enclose an inner space; and a second ring-shaped wall (159; 259; 359) disposed at an outer circumferential portion of the first ring-shaped wall (158; 358); and characterized in that the scroll compressor further comprises: a check valve installed at an inner space of the first ring-shaped wall (158; 358), the check valve being configured to prevent a refrigerant of the discharge space from backflowing to the discharge chamber using a pressure difference between the discharge space and the discharge chamber; and a valve guide (158b; 358b) formed at the inner space of the first ring-shaped wall (158; 358) to guide movement of the check valve; and at least one intermediate discharge opening (158d; 358d) configured to allow flow the refrigerant discharged from the discharge chamber to the discharge space. a casing; a discharge cover, the discharge cover dividing an inner space of the casing into a suction space and a discharge space; a main frame, the main frame being spaced apart from the discharge cover; a first scroll supported by the main frame, the first scroll being configured to perform an orbital motion with respect to a rotational shaft in operation; a second scroll (140; 340) forming a suction chamber, an intermediate pressure chamber, and a discharge chamber together with the first scroll, the second scroll (140; 340) being movable with respect to the first scroll; a back pressure plate (150; 250; 350) coupled to the second scroll (140; 340), the back pressure plate (150; 250; 350) comprising a cavity with which the intermediate pressure chamber of the second scroll (140; 340) communicates, a lower surface of the back pressure plate (150; 250; 350) facing an upper surface of the second scroll (140; 340); and a floating plate movably coupled to the back pressure plate (150; 250; 350) so as to seal an upper portion of the cavity, a supporting plate (152; 352), the supporting plate (152; 352) contacting an upper surface of the second scroll (140; 340); a first ring-shaped wall (158; 358) formed to enclose an inner space; and a second ring-shaped wall (159; 259; 359) disposed at an outer circumferential portion of the first ring-shaped wall (158; 358); and characterized in that the scroll compressor further comprises: a check valve installed at an inner space of the first ring-shaped wall (158; 358), the check valve being configured to prevent a refrigerant of the discharge space from backflowing to the discharge chamber using a pressure difference between the discharge space and the discharge chamber; and a valve guide (158b; 358b) formed at the inner space of the first ring-shaped wall (158; 358) to guide movement of the check valve; and at least one intermediate discharge opening (158d; 358d) configured to allow flow the refrigerant discharged from the discharge chamber to the discharge space. a check valve installed at an inner space of the first ring-shaped wall (158; 358), the check valve being configured to prevent a refrigerant of the discharge space from backflowing to the discharge chamber using a pressure difference between the discharge space and the discharge chamber; and a valve guide (158b; 358b) formed at the inner space of the first ring-shaped wall (158; 358) to guide movement of the check valve; and at least one intermediate discharge opening (158d; 358d) configured to allow flow the refrigerant discharged from the discharge chamber to the discharge space.