PURPOSE: To confirm the use condition of seats and the presence/absence of reservation tickets on a monitor by connecting a passenger monitor terminal and a seat unit, which has a function to detect the existence of a human body, by a signal line to perform communication between them.

CONSTITUTION: When a passenger sits down in a seat, a weight detecting part 6 of a seat unit 3 detects it. When the passenger inserts a card IC, which uses a magnetic card or an IC card where data of departure and arrival stations, the seat number, etc., is recorded, to a card read/write part 7, data is read by the card read/write part 7. A control part 5 collates the seat number set by a seat number setting part 10 with data read from the card 11; and when this data is correct, a signal indicating that the seat is occupied is sent to a passenger monitor terminal 1 through a communication part 4 and a signal line 2. If the weight detecting part 6 detects sitting-down of the passenger but the card 11 is not inserted, an alarm is raised. Thus, the use condition of reserved seats and the presence/absence of reserving tickets can be confirmed.