A scroll compressor comprising: a main body; a fixed scroll fixedly installed in the main body; an orbiting scroll configured to engage with the fixed scroll and perform a relative orbiting motion, and to form a compression chamber with the fixed scroll; a partition plate disposed above the fixed scroll to separate an inside of the main body into a low-pressure portion, L, and a high-pressure portion, H; a valve seat member attached to the partition plate; a first check valve installed at a discharge port of the fixed scroll to open and close the discharge port; a second check valve mounted on the valve seat member to open and close an opening allowing communication between the low-pressure portion and the high-pressure portion; and characterised by: a back pressure chamber disposed between the fixed scroll and the partition plate, and formed by a discharge guide provided on the fixed scroll and a back pressure actuator installed on the discharge guide to be movable in a vertical direction; and a sealing member disposed to seal a gap, G, between the discharge guide and the back pressure actuator to seal the back pressure chamber, wherein the sealing member has a cutout portion that is partially cut for the sealing member to be movable in the vertical direction, and the cutout portion has an inclined surface, wherein during operation of the scroll compressor, the back pressure actuator moves upward so as to be in close contact with a lower portion of the valve seat member by a high pressure of the back pressure chamber such that the inside of the main body is separated into the high-pressure portion and the low-pressure portion, wherein while the scroll compressor is stopped, the back pressure actuator moves downward to be separated from the valve seat member by the low pressure of the back pressure chamber such that a pressure difference is relieved inside the main body, and while the scroll compressor is stopped, the sealing member is moved upward by a high pressure of the back pressure chamber such that refrigerant in the back pressure chamber flows out of the back pressure chamber through the gap, G. a main body; a fixed scroll fixedly installed in the main body; an orbiting scroll configured to engage with the fixed scroll and perform a relative orbiting motion, and to form a compression chamber with the fixed scroll; a partition plate disposed above the fixed scroll to separate an inside of the main body into a low-pressure portion, L, and a high-pressure portion, H; a valve seat member attached to the partition plate; a first check valve installed at a discharge port of the fixed scroll to open and close the discharge port; a second check valve mounted on the valve seat member to open and close an opening allowing communication between the low-pressure portion and the high-pressure portion; and characterised by: a back pressure chamber disposed between the fixed scroll and the partition plate, and formed by a discharge guide provided on the fixed scroll and a back pressure actuator installed on the discharge guide to be movable in a vertical direction; and a sealing member disposed to seal a gap, G, between the discharge guide and the back pressure actuator to seal the back pressure chamber, wherein the sealing member has a cutout portion that is partially cut for the sealing member to be movable in the vertical direction, and the cutout portion has an inclined surface, wherein during operation of the scroll compressor, the back pressure actuator moves upward so as to be in close contact with a lower portion of the valve seat member by a high pressure of the back pressure chamber such that the inside of the main body is separated into the high-pressure portion and the low-pressure portion, wherein while the scroll compressor is stopped, the back pressure actuator moves downward to be separated from the valve seat member by the low pressure of the back pressure chamber such that a pressure difference is relieved inside the main body, and while the scroll compressor is stopped, the sealing member is moved upward by a high pressure of the back pressure chamber such that refrigerant in the back pressure chamber flows out of the back pressure chamber through the gap, G. a back pressure chamber disposed between the fixed scroll and the partition plate, and formed by a discharge guide provided on the fixed scroll and a back pressure actuator installed on the discharge guide to be movable in a vertical direction; and a sealing member disposed to seal a gap, G, between the discharge guide and the back pressure actuator to seal the back pressure chamber, wherein the sealing member has a cutout portion that is partially cut for the sealing member to be movable in the vertical direction, and the cutout portion has an inclined surface, wherein during operation of the scroll compressor, the back pressure actuator moves upward so as to be in close contact with a lower portion of the valve seat member by a high pressure of the back pressure chamber such that the inside of the main body is separated into the high-pressure portion and the low-pressure portion, wherein while the scroll compressor is stopped, the back pressure actuator moves downward to be separated from the valve seat member by the low pressure of the back pressure chamber such that a pressure difference is relieved inside the main body, and while the scroll compressor is stopped, the sealing member is moved upward by a high pressure of the back pressure chamber such that refrigerant in the back pressure chamber flows out of the back pressure chamber through the gap, G.