A push handle comprises a pair of column support portions provided on left and right sides and extendable/contractible in a vertical direction, a holding rod portion integrally interposed between upper ends of the pair of column support portions and extends toward left and right outer sides of the column support portions, and column support lock locking an extended posture of the column support portion. A entire length of the column support portion when contracted is set to be shorter than one of longitudinal and lateral lengths of the loading platform surface, an entire length of the holding rod portion is set to be shorter than the other of the longitudinal and lateral lengths of the loading platform surface to allow fitting in an accommodating groove portion when the push handle is folded.