A dual sealing ball valve comprises a valve body, conduit line connectors coupled to both sides of the valve body, a hollow ball disposed in the valve body, a sheet holder mounted on an inner circumferential surface of at least one of the conduit line connectors, a main sheet tightly contacting the ball around an inlet of the hollow ball, and an elastic sheet mounted on the front surface of the sheet holder. The sheet holder includes a sheet ring supporting the main sheet and the elastic sheet in a front direction, supporting the elastic sheet towards the main sheet, and pushed in the front direction by a pressurizing retainer and a sheet cap coupled to the sheet ring and contacting the main sheet to pressurize the main sheet in a rear direction and towards the elastic sheet.