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An excavator includes an electric load, an electrical energy storage unit including an electrical energy storage part (19) that supplies electric power to the electric load, and a control unit (30) that controls an amount of charge to the electrical energy storage part (19) so that a charge rate of the electrical energy storage part (19) is between a system control upper limit value and a system control lower limit value. The control unit (30) controls the amount of charge to the electrical energy storage part (19) based on a changing trend of a detection value of the charge rate.