A corporate mileage performing service system and a corporate mileage service performing method allow a corporation who has borne the expenses of business trips using airplanes to receive miles of a mileage service. The corporate mileage performing system has a boarding acceptance terminal, a boarding reservation terminal, a boarder information database device, a mileage information database device storing attribute information of corporate mileage service members and personal mileage service members and information about accumulated miles earned by the corporate mileage service members and the personal mileage service members, a corporation vs. individual relationship information database device storing information of personal mileage identification numbers of employees of corporations registered for a corporate mileage service. The mileage information database device asks the corporation vs. individual relationship information database device for information as to whether a boarder is an employee of one of the corporations registered for the corporate mileage service. If the boarder is an employee, then earned miles are added to accumulated miles of the corporation.