To prevent the lock to be made by a mischief when automatically locking a lock device in the full closing attitude of a door body in an electric sliding door arranged in an entrance part of a private room such as a toilet for a handicapped person.

A get-in/out detecting sensor 16 for detecting get-in/out of a room and an automatic lock device 13 for locking a door body 1 in the closing attitude are connected to a control unit 9 for controlling the drive of an opening/closing machine 7. The control unit 9 is provided with a count means 17 for counting the number of detection of the get-in/out detecting sensor 16 and a lock control means 18 for determining to reject the lock by the automatic lock device 13 when the number of detection by the count means 17 is an even number containing zero and for determining to automatically lock when the number of detection is an odd number.