Abstract: A method and apparatus for determining a vertical driving state using a sensor which determines the driving state according to a gravity change of a moving object by using an acceleration sensor are provided. The method of determining a driving state using a sensor includes: reading a sensor output signal according to a gravity value of a moving object while being driven, from a sensor which senses a gravity value of the moving object with respect to a direction of gravity; and determining whether the moving object is in a level driving state or inclining/declining-slope driving state by comparing the read sensor output signal with a predetermined reference range.