A vehicle valve comprising: a housing in which a flow path is formed and a shaft hole is formed in a direction orthogonal to the flow path; a driving part provided in the housing; an opening and closing part including a shaft connected to the driving part and a plate coupled to the shaft and selectively opening and closing the flow path, and controlling flow of gas passing through the flow path; and wherein the opening and closing part includes a sealing member coupled to a sealing groove formed on an outer circumferential surface of the plate to shield between the flow path inner circumferential surface and the plate and disposed to horizontally move in a width direction of the sealing groove, the vehicle valve further comprising a square ring that contacts the sealing member when being disposed around the plate to close the opening and closing part inside the flow path, and including at least one planar portion in a circumferential direction on an outer circumferential surface, wherein, in the opening and closing part, the plate is disposed at a position spaced apart from a rotation shaft of the shaft, wherein the square ring includes: a cylindrical portion including a hollow portion; and a through hole through which the shaft is inserted; wherein the cylindrical portion includes: a first region disposed at one side of the cylindrical portion; a second region disposed at the other side of the cylindrical portion; and a third region being a portion connecting the first region and the second region and having an inner circumferential surface formed of a curved surface or an inclined surface, wherein the first region has the largest thickness among the first region, second region and third region, wherein the second region has an inner circumferential surface, wherein the inner circumferential surface comes into contact with the plate or the sealing member in a process of closing the opening and closing part, and is made of a curved surface or an inclined surface shape. a housing in which a flow path is formed and a shaft hole is formed in a direction orthogonal to the flow path; a driving part provided in the housing; an opening and closing part including a shaft connected to the driving part and a plate coupled to the shaft and selectively opening and closing the flow path, and controlling flow of gas passing through the flow path; and wherein the opening and closing part includes a sealing member coupled to a sealing groove formed on an outer circumferential surface of the plate to shield between the flow path inner circumferential surface and the plate and disposed to horizontally move in a width direction of the sealing groove, the vehicle valve further comprising a square ring that contacts the sealing member when being disposed around the plate to close the opening and closing part inside the flow path, and including at least one planar portion in a circumferential direction on an outer circumferential surface, wherein, in the opening and closing part, the plate is disposed at a position spaced apart from a rotation shaft of the shaft, wherein the square ring includes: a cylindrical portion including a hollow portion; and a through hole through which the shaft is inserted; wherein the cylindrical portion includes: a first region disposed at one side of the cylindrical portion; a second region disposed at the other side of the cylindrical portion; and a third region being a portion connecting the first region and the second region and having an inner circumferential surface formed of a curved surface or an inclined surface, wherein the first region has the largest thickness among the first region, second region and third region, wherein the second region has an inner circumferential surface, wherein the inner circumferential surface comes into contact with the plate or the sealing member in a process of closing the opening and closing part, and is made of a curved surface or an inclined surface shape. a cylindrical portion including a hollow portion; and a through hole through which the shaft is inserted; wherein the cylindrical portion includes: a first region disposed at one side of the cylindrical portion; a second region disposed at the other side of the cylindrical portion; and a third region being a portion connecting the first region and the second region and having an inner circumferential surface formed of a curved surface or an inclined surface, wherein the first region has the largest thickness among the first region, second region and third region, wherein the second region has an inner circumferential surface, wherein the inner circumferential surface comes into contact with the plate or the sealing member in a process of closing the opening and closing part, and is made of a curved surface or an inclined surface shape. a first region disposed at one side of the cylindrical portion; a second region disposed at the other side of the cylindrical portion; and a third region being a portion connecting the first region and the second region and having an inner circumferential surface formed of a curved surface or an inclined surface, wherein the first region has the largest thickness among the first region, second region and third region, wherein the second region has an inner circumferential surface, wherein the inner circumferential surface comes into contact with the plate or the sealing member in a process of closing the opening and closing part, and is made of a curved surface or an inclined surface shape.