To provide an openable door stopper device which positively prevents an openable door of a fume hood (draft chamber) from being unnecessarily opened to an opening in excess of a restriction location during an experiment by an experimenter, and avoids a dangerous event caused by lowering of a control wind speed to a value below a safety standard.

According to the openable door stopper device, a stopper 20 that forcibly stops the door 5 at an intermediate location in the process of opening operation, is provided with a lock device 20 for locking the stopper at a stopping location. The lock device 20 is unlockable by only unlocking operation of a specific person holding a key 31.