When one of an acquired plurality of parameters that represents an exercise state of a subject changes or is assumed to change, a value of another parameter that changes in conjunction with that change is estimated. A parameter acquirer acquires, as indexes representing the exercise state of the subject, a value of a first parameter, a value of a second parameter that is an index different from and having a correlation with the first parameter, and another first parameter that is the first parameter having a value that differs from the acquired value of the first parameter. A parameter estimator estimates the value of the second parameter that corresponds to the another first parameter in accordance with a model generated based on sets of a value of a third parameter as an input of the model and a fourth parameter as an output of the model.