An acetone concentration estimate device acquires a measured acetone concentration measuring acetone excreted from a user, acquires an elapsed time which has elapsed since the user ate a meal, and estimates an acetone concentration, which is a ketone body concentration of when an amount of change in blood sugar level of the user per given unit of time is stable, based on the acquired current measured acetone concentration and on the acquired elapsed time, and outputs information corresponding to the estimated acetone concentration.