A method of generating a finger image includes determining a quantity of electric charge to be removed from each of a plurality of detection circuits connected to a fingerprint sensor, based on an amplifier characteristic of each of the plurality of detection circuits; obtaining a second electrical quantity by removing the quantity of electric charge from a first electrical quantity that is input to each of the plurality of detection circuits; integrating the second electrical quantity to obtain an integrated value; and generating the fingerprint image based on comparison between the integrated value of the second electrical quantity and a predetermined threshold value.