In a heart rate estimating apparatus, a sensor generates pulse wave data indicating a pulse wave of a body. A storage unit stores a plurality of state transition models each representing states including a normal state and an abnormal state corresponding to noise, transition probabilities between the states, and output probabilities of a plurality of different symbols, wherein at least one of the transition probabilities and the output probabilities differs between the respective state transition models. An estimating unit generates a symbol string that indicates a time series of changes in the pulse wave from the pulse wave data, calculates a fit between the symbol string and each of the plurality of state transition models, and calculates a heart rate estimated from the pulse wave data based on a state transition model selected in accordance with the fit.
