To provide a simple vehicle preventing loss of easy entrance even when the height of a side sill is slightly increased, and reducing an increase in the frontal projected area of the vehicle as much as possible.

A substantially container-shaped under-carriage 15 is provided, with its upper side opened while synthetic resin-made side sills 22 are arranged with a space therebetween on both sides in the width direction of a floor member 21. A window frame member 16 is attachably/detachably fixed to a front upper part of the under-carriage 15, and an entrance door 17 is mounted on a rear upper part in a backwardly retractable manner. An occupant can stand up while the entrance door is backwardly retracted, and the occupant can easily enter the vehicle across the side sill even when it is high.