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 hot water and cold 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, wherein a hole opens in an axial center part of one end of said casing, said main body member comprises: a biasing member made of a material having a fixed spring constant, an actuator which expands or shrinks according to a temperature change, a control valve member in which one end is subjected to a load from said biasing member and the other end is subjected to a load from said actuator, 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 actuator, and a temperature adjusting means (8, 9) whose one side is fixed to said temperature adjusting dial and which moves said biasing member according to rotation of said temperature adjusting dial to apply a load to said control valve member and to set up a position of said control valve member, and is formed in the shape of a cylinder, wherein an upper surface is formed at one cylindrical end of said temperature adjusting means (8, 9), a knob which is substantially cylindrical and fixed to said temperature adjusting dial is formed in the center of said upper surface, and said temperature adjusting means (8, 9) is arranged inside one end of said casing and coaxially with said casing and said knob is rotatably inserted into the hole which opens at one end of said casing, characterized in that a ring-shaped recess concentric with said knob is formed at the peripheral part of said knob at said upper surface; and a spacer for covering the recess formed at said upper surface is interposed and held between the upper surface of said temperature adjusting means (8, 9) and one end of said casing. 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 hot water and cold 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, wherein a hole opens in an axial center part of one end of said casing, said main body member comprises: a biasing member made of a material having a fixed spring constant, an actuator which expands or shrinks according to a temperature change, a control valve member in which one end is subjected to a load from said biasing member and the other end is subjected to a load from said actuator, 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 actuator, and a temperature adjusting means (8, 9) whose one side is fixed to said temperature adjusting dial and which moves said biasing member according to rotation of said temperature adjusting dial to apply a load to said control valve member and to set up a position of said control valve member, and is formed in the shape of a cylinder, wherein an upper surface is formed at one cylindrical end of said temperature adjusting means (8, 9), a knob which is substantially cylindrical and fixed to said temperature adjusting dial is formed in the center of said upper surface, and said temperature adjusting means (8, 9) is arranged inside one end of said casing and coaxially with said casing and said knob is rotatably inserted into the hole which opens at one end of said casing, a biasing member made of a material having a fixed spring constant, an actuator which expands or shrinks according to a temperature change, a control valve member in which one end is subjected to a load from said biasing member and the other end is subjected to a load from said actuator, 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 actuator, and a temperature adjusting means (8, 9) whose one side is fixed to said temperature adjusting dial and which moves said biasing member according to rotation of said temperature adjusting dial to apply a load to said control valve member and to set up a position of said control valve member, and is formed in the shape of a cylinder, wherein an upper surface is formed at one cylindrical end of said temperature adjusting means (8, 9), a knob which is substantially cylindrical and fixed to said temperature adjusting dial is formed in the center of said upper surface, and said temperature adjusting means (8, 9) is arranged inside one end of said casing and coaxially with said casing and said knob is rotatably inserted into the hole which opens at one end of said casing, a ring-shaped recess concentric with said knob is formed at the peripheral part of said knob at said upper surface; and a spacer for covering the recess formed at said upper surface is interposed and held between the upper surface of said temperature adjusting means (8, 9) and one end of said casing.