A battery is integrated with a down frame and a bottom frame. When fixation of the battery to a main frame is released upon release of locking means, the down frame, the bottom frame, and the battery are allowed to swing pivotally around an engagement position where the bottom frame is engaged with pivot frames. A front wheel is located on at least any one of swing loci of the down frame, the bottom frame, and the battery drawn when the down frame, the bottom frame, and the battery swing pivotally around the engagement position. The front wheel deviates from the swing locus in a state where the handlebar is turned.