An electronic control unit configured to be included in a hybrid vehicle, and further configured to i) calculate a utilization index of charging of a battery by a battery charger based on a ratio of an electric traveling utilization level to a hybrid traveling utilization level or a ratio of the electric traveling utilization level to a total traveling utilization level; and ii) store the calculated utilization index characterized in that the electronic control unit is configured to calculate the utilization index based on at least one of a) a ratio of the number of times that the battery charger charges the battery to the number of trips, and b) a ratio of total time of connecting the battery charger to an external power supply to total vehicle stop time with a system of the vehicle being turned off, c) a ratio of total electric traveling time achieved without involving operation of an engine to total hybrid traveling time achieved involving operation of the engine, d) a ratio of the total electric traveling distance to a total traveling distance, e) a ratio of the total electric traveling time to total traveling time, f) a ratio of an integrated value of energy used to charge the battery by the battery charger to an integrated value of energy consumed for traveling, g) a ratio of a total charge amount of the battery charged by the battery charger to a total fuel supply quantity to a fuel tank, and h) a ratio of the total traveling distance to total emission of carbon dioxide, wherein the electronic control unit is configured to calculate the utilization index such that influence of a vehicle utilization status on the utilization index is smaller in a trip with a large traveling distance than in a trip with a small traveling distance, based on at least one of c) the ratio of the total electric traveling time to the total hybrid traveling time, d) the ratio of the total electric traveling distance to the total traveling distance, e) the ratio of the total electric traveling time to the total traveling time, and g) the ratio of the total charge amount of the battery charged by the battery charger to the total fuel supply quantity to the fuel tank. i) calculate a utilization index of charging of a battery by a battery charger based on a ratio of an electric traveling utilization level to a hybrid traveling utilization level or a ratio of the electric traveling utilization level to a total traveling utilization level; and ii) store the calculated utilization index the electronic control unit is configured to calculate the utilization index based on at least one of a) a ratio of the number of times that the battery charger charges the battery to the number of trips, and b) a ratio of total time of connecting the battery charger to an external power supply to total vehicle stop time with a system of the vehicle being turned off, c) a ratio of total electric traveling time achieved without involving operation of an engine to total hybrid traveling time achieved involving operation of the engine, d) a ratio of the total electric traveling distance to a total traveling distance, e) a ratio of the total electric traveling time to total traveling time, f) a ratio of an integrated value of energy used to charge the battery by the battery charger to an integrated value of energy consumed for traveling, g) a ratio of a total charge amount of the battery charged by the battery charger to a total fuel supply quantity to a fuel tank, and h) a ratio of the total traveling distance to total emission of carbon dioxide, a) a ratio of the number of times that the battery charger charges the battery to the number of trips, and b) a ratio of total time of connecting the battery charger to an external power supply to total vehicle stop time with a system of the vehicle being turned off, c) a ratio of total electric traveling time achieved without involving operation of an engine to total hybrid traveling time achieved involving operation of the engine, d) a ratio of the total electric traveling distance to a total traveling distance, e) a ratio of the total electric traveling time to total traveling time, f) a ratio of an integrated value of energy used to charge the battery by the battery charger to an integrated value of energy consumed for traveling, g) a ratio of a total charge amount of the battery charged by the battery charger to a total fuel supply quantity to a fuel tank, and h) a ratio of the total traveling distance to total emission of carbon dioxide, wherein the electronic control unit is configured to calculate the utilization index such that influence of a vehicle utilization status on the utilization index is smaller in a trip with a large traveling distance than in a trip with a small traveling distance, based on at least one of c) the ratio of the total electric traveling time to the total hybrid traveling time, d) the ratio of the total electric traveling distance to the total traveling distance, e) the ratio of the total electric traveling time to the total traveling time, and g) the ratio of the total charge amount of the battery charged by the battery charger to the total fuel supply quantity to the fuel tank.