To provide a door structure of a cabin for expanding the whole surface visibility of a door, and formable into a compact and inexpensive constitution, by forming the door for opening-closing by sliding in a boarding-alighting port out of a door plate formed of a single transparent plate.

This cabin 2 has the door 1 for opening-closing the boarding-alighting port 1a by sliding in the longitudinal direction; and is constituted so that the door plate 15 of the door 1 is formed of the single transparent plate; a seal member 19 abutting on an outside surface of a door frame 55 in closing, is stretched along the outer periphery of the door plate 15; an intermediate guide rail 26 is arranged in the width direction in an inside intermediate height position on the door plate 15; and an intermediate guide part 31 for slidably engaging and supporting the intermediate guide rail 26, is arranged inside the boarding-alighting port 1a formed of the door frame 55.