A ladder device includes a ladder main body, a hand railing, a driving mechanism and a coupling member. One end of the coupling member is pivotably supported by the ladder main body, while the other end thereof is pivotably supported by the hand railing. The coupling member is configured to: position the hand railing between the ladder main body and a walkway when the ladder main body takes the deployed posture; pivot the hand railing in conjunction with a pivot action of the ladder main body from the deployed posture to the retracted posture; and position the hand railing further inwards of the vehicle body than the ladder main body is when the ladder main body takes the retracted posture.