A hot and cold water mixing valve, comprising: a temperature adjusting dial which is subjected to temperature control operation, and a main body member having a control valve mechanism for adjusting temperatures of mixed water by operating said temperature adjusting dial and a casing in which a hot water inlet (a) and a cold water inlet (b) are formed and said control valve mechanism is accommodated, and said main body member further comprising: a biasing member made of a material having a fixed spring constant, a temperature sensitive spring which expands or shrinks according to a temperature change, and a control valve member in which a first spring bracket for supporting said biasing member is abutted against one end, and a second spring bracket for supporting said temperature sensitive spring is abutted against the other end, and an opening/closing ratio between said hot water inlet (a) and said cold water inlet (b) is changed by balancing between the loads applied by said biasing member and said temperature sensitive spring, to adjust a mixture ratio between the hot water which flows in through said hot water inlet (a) and the cold water which flows in through said cold water inlet (b), characterized in that a mixing chamber for mixing the cold water from said cold water inlet (a) and the hot water from said hot water inlet (b) is provided inside said casing, and a third spring bracket for supporting said temperature sensitive spring is formed in said mixing chamber, said temperature sensitive spring is constituted by a coil-like large diameter coil spring wound to have a large diameter and a coil-like small diameter coil spring wound to have a small diameter, and said large diameter coil spring and said small diameter coil spring are arranged so that their axes are coaxial or in parallel, and supported between said second spring bracket and third spring bracket, and a cylindrical cover surrounding a perimeter side of said small diameter coil spring is formed integrally or substantially integrally with said second spring bracket or the third spring bracket, the perimeter side of said small diameter coil spring is enclosed with the cover on an inner circumference side of said large diameter coil spring, and a response of expansion/shrink operation according to the temperature change of said large diameter coil spring and a response of expansion/shrink operation according to the temperature change of said small diameter coil spring are differentiated. a temperature adjusting dial which is subjected to temperature control operation, and a main body member having a control valve mechanism for adjusting temperatures of mixed water by operating said temperature adjusting dial and a casing in which a hot water inlet (a) and a cold water inlet (b) are formed and said control valve mechanism is accommodated, and said main body member further comprising: a biasing member made of a material having a fixed spring constant, a temperature sensitive spring which expands or shrinks according to a temperature change, and a control valve member in which a first spring bracket for supporting said biasing member is abutted against one end, and a second spring bracket for supporting said temperature sensitive spring is abutted against the other end, and an opening/closing ratio between said hot water inlet (a) and said cold water inlet (b) is changed by balancing between the loads applied by said biasing member and said temperature sensitive spring, to adjust a mixture ratio between the hot water which flows in through said hot water inlet (a) and the cold water which flows in through said cold water inlet (b), a biasing member made of a material having a fixed spring constant, a temperature sensitive spring which expands or shrinks according to a temperature change, and a control valve member in which a first spring bracket for supporting said biasing member is abutted against one end, and a second spring bracket for supporting said temperature sensitive spring is abutted against the other end, and an opening/closing ratio between said hot water inlet (a) and said cold water inlet (b) is changed by balancing between the loads applied by said biasing member and said temperature sensitive spring, to adjust a mixture ratio between the hot water which flows in through said hot water inlet (a) and the cold water which flows in through said cold water inlet (b), a mixing chamber for mixing the cold water from said cold water inlet (a) and the hot water from said hot water inlet (b) is provided inside said casing, and a third spring bracket for supporting said temperature sensitive spring is formed in said mixing chamber, said temperature sensitive spring is constituted by a coil-like large diameter coil spring wound to have a large diameter and a coil-like small diameter coil spring wound to have a small diameter, and said large diameter coil spring and said small diameter coil spring are arranged so that their axes are coaxial or in parallel, and supported between said second spring bracket and third spring bracket, and a cylindrical cover surrounding a perimeter side of said small diameter coil spring is formed integrally or substantially integrally with said second spring bracket or the third spring bracket, the perimeter side of said small diameter coil spring is enclosed with the cover on an inner circumference side of said large diameter coil spring, and a response of expansion/shrink operation according to the temperature change of said large diameter coil spring and a response of expansion/shrink operation according to the temperature change of said small diameter coil spring are differentiated.