A thermostat device , comprising: a housing ; a thermal-operating unit , wherein the thermal-operating unit is accommodated in the thermostat and is arranged to be disposed in a circulation passage that circulates a coolant between an internal combustion engine and a radiator and controls temperature of the coolant to be supplied to the internal combustion engine; the thermal-operating unit comprising: a thermo-sensitive element containing a thermal expansion body therein that expands or contracts in response to the temperature change of the coolant; a control valve opening or closing the flow passage in the housing based on the expansion or contraction of the thermal expansion body; a spring biasing so as to close the control valve ; a spring receiving frame receiving one end of the spring ; a locking portion formed on the spring receiving frame ; and the housing further comprising a frame support , wherein the thermal-operating unit is incorporated by locking the spring receiving frame to the frame support formed in the flow passage of the housing , and wherein the rectifier is disposed at an upstream side of the coolant flow at the frame support to prevent a collision of coolant flow against the frame support and the spring receiving frame by causing the coolant flow forwarding to the frame support and the spring receiving frame to detour, characterized in that the rectifier is disposed projecting along the flow passage of the housing , the central portion of the rectifier is located on the upstream side of the flow of the coolant, and both legs thereof are located on the downstream side relative to the central portion. a housing ; a thermal-operating unit , wherein the thermal-operating unit is accommodated in the thermostat and is arranged to be disposed in a circulation passage that circulates a coolant between an internal combustion engine and a radiator and controls temperature of the coolant to be supplied to the internal combustion engine; the thermal-operating unit comprising: a thermo-sensitive element containing a thermal expansion body therein that expands or contracts in response to the temperature change of the coolant; a control valve opening or closing the flow passage in the housing based on the expansion or contraction of the thermal expansion body; a spring biasing so as to close the control valve ; a spring receiving frame receiving one end of the spring ; a locking portion formed on the spring receiving frame ; and the housing further comprising a frame support , a thermo-sensitive element containing a thermal expansion body therein that expands or contracts in response to the temperature change of the coolant; a control valve opening or closing the flow passage in the housing based on the expansion or contraction of the thermal expansion body; a spring biasing so as to close the control valve ; a spring receiving frame receiving one end of the spring ; a locking portion formed on the spring receiving frame ; and the housing further comprising a frame support , wherein the thermal-operating unit is incorporated by locking the spring receiving frame to the frame support formed in the flow passage of the housing , and <EOS>