Heating value derivation device and heating value derivation method

Provided are a heating value derivation device and a calorific value derivation method that allow a cost reduction to be achieved. A gas meter (calorific value derivation device) 110 is provided with a sonic speed derivation unit 160 that derives the sonic speed of gas flowing through a gas flow path, a calorific value derivation unit 164 that refers to correspondence relation information by which the calorific value per unit volume of gas is unambiguously derivable from the gas sonic speed and derives the calorific value per unit volume of gas, regardless of the type of gas, on the basis of the sonic speed derived by the sonic speed derivation unit 160, and a flow rate derivation unit 162 that derives the flow rate of gas that has passed through the gas flow path. Thereby, it is possible to derive the calorific value of gas that has passed through the meter. 提供能够实现低成本化的发热量导出装置及发热量导出方法。燃气表(发热量导出装置)(110)具有：声速导出部(160)，其导出在燃气流路内流过的燃气的声速；发热量导出部(164)，其参照根据燃气的声速唯地导出每单位体积的发热量的对应关系信息，根据由声速导出部(160)导出的声速，导出与该燃气的类别无关的、该