PURPOSE: To prevent a passenger from entering a driver's seat by mistake and prevent an enclosing door from becoming a hindrance at interior cleaning time or inspection and maintenance time of the driver's seat.

CONSTITUTION: A rear enclosure 13 to partition a driver's seat 11 and passenger seats is extendedly arranged in the car width direction behind the driver's seat 11 of a bus 10, and a side enclosure 14 whose rear end is connected to one end of the rear enclosure 13 extends in the advancing direction of the bus 10, and is situated on the side of the driver's seat 11. A driver use passage 17 through which a driver can pass is formed between the front end of the side enclosure 14 and an instrument panel 16, and an enclosing door 18 closes this driver use passage 17 so as to be openable. The enclosing door 18 is formed in an extensible-contractible bellows shape, and a recessed part 26 having almost the same height with a height of the enclosing door 18 is formed on a front surface of the side enclosure 14. The rear end of the enclosing door 18 is installed in the recessed part 26, and the enclosing door 18 is housed in the recessed part 26 in a contracted condition.