A control valve comprising: a valve main body in which a valve chamber is formed in its inner portion; a connection member which is firmly fixed to the valve main body; and a can which is firmly fixed to the valve main body, wherein the valve main body and the can include the same metal material, wherein the valve main body is made of stainless steel and the can is made of stainless steel, wherein the valve main body and the can are firmly fixed by welding, wherein the connection member is made of a resin and is configured to be positioned away from the welded portion, wherein the connection member is provided with a fastening portion for connecting piping parts, wherein the valve main body has a first piping which defines a first flow path and which is provided with a first flange portion and a second piping which defines a second flow path and which is provided with a second flange portion at its end, wherein the connection member has a first flange receiving portion which is arranged in the periphery of the first piping and a second flange receiving portion which is arranged in the periphery of the second piping, wherein the first flange receiving portion and the second flange receiving portion are disposed oppositely and connected via the fastening portion, wherein the connection member is provided with only one fastening portion at an eccentric position from a central axis of the first piping, and wherein the fastening portion has a hole portion through which fastening members (F1, F2) are adapted to be inserted to connect the piping parts with the fastening portion at the first flange receiving portion side and at the second flange receiving portion side of the connection member, respectively. a valve main body in which a valve chamber is formed in its inner portion; a connection member which is firmly fixed to the valve main body; and a can which is firmly fixed to the valve main body, wherein the valve main body and the can include the same metal material, wherein the valve main body is made of stainless steel and the can is made of stainless steel, wherein the valve main body and the can are firmly fixed by welding, wherein the connection member is made of a resin and is configured to be positioned away from the welded portion, wherein the connection member is provided with a fastening portion for connecting piping parts, wherein the valve main body has a first piping which defines a first flow path and which is provided with a first flange portion and a second piping which defines a second flow path and which is provided with a second flange portion at its end, wherein the connection member has a first flange receiving portion which is arranged in the periphery of the first piping and a second flange receiving portion which is arranged in the periphery of the second piping, wherein the first flange receiving portion and the second flange receiving portion are disposed oppositely and connected via the fastening portion, wherein the connection member is provided with only one fastening portion at an eccentric position from a central axis of the first piping, and wherein the fastening portion has a hole portion through which fastening members (F1, F2) are adapted to be inserted to connect the piping parts with the fastening portion at the first flange receiving portion side and at the second flange receiving portion side of the connection member, respectively.