There is provided a barometric altimeter to detect a floor number at the current position in especially a high-rise building, and to calculate a height or a floor number more precisely. To this end, a barometric altimeter (100) stores, at a barometric pressure/height conversion coefficient storage unit (2), a plurality of barometric pressure/height conversion coefficients that is calculated beforehand based on temperature of air indoors in accordance with a month and a date, and an arithmetic expression, for which the plurality of barometric pressure/height conversion coefficients are used. For the actual operation, while a reference barometric pressure measurement/storage unit (1) measures and stores a barometric pressure at a position as reference barometric pressure, a current barometric pressure measurement unit (3) measures the barometric pressure at the position to be measured. Then a height calculation unit (5) calculates the height through predetermined calculation using the result of processing at these blocks.