A calorific value measuring system, comprising: a pipe configured to comprise a fluid that flows; a flow rate controlling device (32A, 32B, 32C, 32D) configured to control a flow rate of the fluid that flows with in the pipe; a temperature measuring element (62, 63) disposed within the pipe; a heater element, disposed within the pipe, configured to produce heat at a plurality of heat producing temperatures; a measuring portion configured to measure a value for an electric signal from a temperature measuring element that is dependent on the temperature of the gas that is flowing within the pipe, and a value for an electric signal from a heater element at each of a plurality of heat producing temperatures; an equation storage device storing a calorific value calculating equation that uses an electric signal from the temperature measuring element and electric signals from the heater element at the plurality of heat producing temperatures as independent variables and uses the calorific value as the dependent variable; and a calorific value calculating portion configured to calculate a value for the calorific value of a gas through substituting a value of an electrical signal from the temperature measuring element and a value of an electric signal from the heater element into the independent variables of the calorific value calculating equation, wherein the temperature measuring element (62, 63) and the heater element are disposed so as to protrude into the pipe and, wherein the temperature measuring element (62, 63) and the heater element are disposed so as to protrude into the pipe at an angle so as to face the gas that is flowing within the pipe. a pipe configured to comprise a fluid that flows; a flow rate controlling device (32A, 32B, 32C, 32D) configured to control a flow rate of the fluid that flows with in the pipe; a temperature measuring element (62, 63) disposed within the pipe; a heater element, disposed within the pipe, configured to produce heat at a plurality of heat producing temperatures; a measuring portion configured to measure a value for an electric signal from a temperature measuring element that is dependent on the temperature of the gas that is flowing within the pipe, and a value for an electric signal from a heater element at each of a plurality of heat producing temperatures; an equation storage device storing a calorific value calculating equation that uses an electric signal from the temperature measuring element and electric signals from the heater element at the plurality of heat producing temperatures as independent variables and uses the calorific value as the dependent variable; and a calorific value calculating portion configured to calculate a value for the calorific value of a gas through substituting a value of an electrical signal from the temperature measuring element and a value of an electric signal from the heater element into the independent variables of the calorific value calculating equation, wherein the temperature measuring element (62, 63) and the heater element are disposed so as to protrude into the pipe and, wherein the temperature measuring element (62, 63) and the heater element are disposed so as to protrude into the pipe at an angle so as to face the gas that is flowing within the pipe.