A cartridge for mixing and injecting bone cement, the cartridge comprising: a body including a cylindrical member having a square cross-section in a lengthwise direction thereof for receiving bone cement, a first coupling means provided at a first open end of the cylindrical member, and a second coupling means provided at a second open end of the cylindrical member; at least one mixing ball provided in an internal space of the body, which internal space is limited by the side wall of the cylindrical member thereof, for mixing bone cement within said internal space; a first opening/closing means detachably coupled with the first coupling means for closing the first open end, through which components of the bone cement are insertable into said internal space and injectable therefrom to an area to be treated; and a second opening/closing means detachably coupled with the second coupling means and including a plunger member provided in the second opening/closing means; characterized in that the second opening/closing means is configured to be coupled to a cement gun after mixing of the bone cement, the plunger member of said second opening/closing means is configured to be pushed by said cement gun into the cylindrical member for injecting bone cement from said internal space to the area to be treated via an injection tube coupled with the cartridge in place of the first opening/closing means after removing the first opening/closing means from the cartridge, and the cartridge further comprises a maintenance member configured to maintain a vacuum of the internal space of the body when mixing the bone cement within said internal space. a body including a cylindrical member having a square cross-section in a lengthwise direction thereof for receiving bone cement, a first coupling means provided at a first open end of the cylindrical member, and a second coupling means provided at a second open end of the cylindrical member; at least one mixing ball provided in an internal space of the body, which internal space is limited by the side wall of the cylindrical member thereof, for mixing bone cement within said internal space; a first opening/closing means detachably coupled with the first coupling means for closing the first open end, through which components of the bone cement are insertable into said internal space and injectable therefrom to an area to be treated; and a second opening/closing means detachably coupled with the second coupling means and including a plunger member provided in the second opening/closing means; characterized in that the second opening/closing means is configured to be coupled to a cement gun after mixing of the bone cement, the plunger member of said second opening/closing means is configured to be pushed by said cement gun into the cylindrical member for injecting bone cement from said internal space to the area to be treated via an injection tube coupled with the cartridge in place of the first opening/closing means after removing the first opening/closing means from the cartridge, and the cartridge further comprises a maintenance member configured to maintain a vacuum of the internal space of the body when mixing the bone cement within said internal space.