A physical quantity measuring apparatus of the present invention measures a physical quantity from a signal based on a physical quantity output by a physical quantity signal output apparatus. A correction signal output unit outputs a new correction signal based on a signal on the basis of a physical quantity obtained at a given measurement time, a correction signal obtained before that measurement time, and a filter coefficient. A large/small relationship determining unit determines a large/small relationship between the signal on the basis of the physical quantity and the correction signal obtained before that measurement time. A first filter coefficient output unit outputs a first filter coefficient based on the plural large/small relationships.