To provide an obstacle detecting device which has a simple structure, which can determine whether it is a contact with an obstacle or a contact with a floor surface, and which can comes to a stop at its lower limit position when a shutter makes contact with the floor surface while a safety can be ensured during opening and closing of the shutter.

A shutter curtain 1 adapted to be moved for opening and closing, is provided at its lower end part with a retainer switch and an proximity sensor 8. The retainer switch can be turned on through the movement of a retainer 4 during contact with an obstacle, and the proximity sensor 8 is energized when it comes down to the position of a magnet 9 provided at the lower limit position of the guide rail. An obstacle detecting part 3 transmits a detection signal when it makes contact with an obstacle, in accordance with detection signals from the retainer switch and the proximity switch 8, and transmits a lower limit signal when it make contact with a floor surface. A control part controls the opening and closing of the shutter in accordance with a received signal.