A circuit body includes a flexible insulation sheet with an electric circuit pattern having wiring patterns and a temperature sensor arranged in the electric circuit pattern. The electric circuit pattern has a temperature-sensor connecting portion and a heat-concentrating pattern formed integrally with the temperature-sensor connecting portion so as to have a larger width than that of the wiring pattern. The temperature sensor is touched through the heat-concentrating pattern to an object to be measured. The wiring patterns and the heat-concentrating pattern are formed integrally on a primary surface of the insulation sheet by printing. An additional heat-concentrating pattern is further formed on a secondary surface of the insulation sheet at a position corresponding to the temperature-sensor connecting portion. The heat-concentrating patterns are bent integrally with the insulation sheet and touched to the object to be measured.