A charge state calculation device, comprising: a detection means (31, 32) configured to detect at least one of a voltage and a current of a battery; a deterioration calculation unit configured to calculate a deterioration degree of the battery from the detected value of the detection means (31, 32); a charge state prediction means configured to predict a full charge absolute SOC before correction based on the deterioration degree; a charge state calculation means configured to calculate the charge state absolute SOC of the battery during charging from the detected value of the detection means (31, 32); a full charge detection means configured to detect the full charge of the battery using the detection means (31, 32); a correction value calculation means configured to, upon full charge being detected by the full charge detection means, calculate a correction value, based on the predicted full charge absolute SOC value and the calculated charge state absolute SOC calculated by the charge state calculation means when the full charge is detected, and to correct the charge state absolute SOC calculated by the charge state calculation means to the charge state of 100%; and a full charge SOC correction unit configured to correct the predicted full charge absolute SOC value by using the correction value calculated by the correction value calculation means; wherein the correction value calculation means is configured to update the correction value only when the full charge of the battery is detected by the full charge detection means and is configured to maintain the updated correction value until next time the full charge of the battery will be detected by the full charge detection means, wherein the charge state calculation device is configured such that a display means displays a ratio of the calculated charge state absolute SOC of the battery to the predicted full charge absolute SOC value corrected by the full charge SOC correction unit. a detection means (31, 32) configured to detect at least one of a voltage and a current of a battery; a deterioration calculation unit configured to calculate a deterioration degree of the battery from the detected value of the detection means (31, 32); a charge state prediction means configured to predict a full charge absolute SOC before correction based on the deterioration degree; a charge state calculation means configured to calculate the charge state absolute SOC of the battery during charging from the detected value of the detection means (31, 32); a full charge detection means configured to detect the full charge of the battery using the detection means (31, 32); a correction value calculation means configured to, upon full charge being detected by the full charge detection means, calculate a correction value, based on the predicted full charge absolute SOC value and the calculated charge state absolute SOC calculated by the charge state calculation means when the full charge is detected, and to correct the charge state absolute SOC calculated by the charge state calculation means to the charge state of 100%; and a full charge SOC correction unit configured to correct the predicted full charge absolute SOC value by using the correction value calculated by the correction value calculation means; wherein the correction value calculation means is configured to update the correction value only when the full charge of the battery is detected by the full charge detection means and is configured to maintain the updated correction value until next time the full charge of the battery will be detected by the full charge detection means, wherein the charge state calculation device is configured such that a display means displays a ratio of the calculated charge state absolute SOC of the battery to the predicted full charge absolute SOC value corrected by the full charge SOC correction unit.