A portable device for evaluating a physical strength is disclosed. The portable device includes a first sensor for sensing walking of a user; a second sensor for sensing heartbeat of the user; and a controller for: measuring a walking speed of the user using a sensed result of the first sensor; measuring a heart rate of the user using a sensed result of the second sensor; and evaluating a physical strength of the user using the measured heart rate when the walking speed of the user is changed by a specific speed or more by comparing a virtual heart rate calculated using the walking speed of the user with the measured heart rate.