PURPOSE: To make it appliable even to the case that a work feed rate is fast without making its structure into complication, by impeding the progress of a work on a conveying passage with a progress preventive device, while detecting the work, whose progress is impeded, and taking it out.

CONSTITUTION: When a belt 2 moves, a control part 21 projects a stopper 3A out, whereby if a work preventing state of a diaphragm 7 is detected by a sensor 12, a stopper 4A is forcibly projected out. Next, when a timer part 22 is started and the work preventing state of a diaphragm 8 is detected by a sensor 13, this timer part 22 is reset. On the other hand, when diaphragms 7W10 come into the work preventing state by all stoppers 3AW6A, these diaphragms 7W10 are taken out with a diaphragm takeout part 16 by control of the control part 21. After taking out, these stoppers 4AW6A are made to go down by the control part 21, providing for the next operation. With this constitution, since the work stopped at the specified position is taken out, its structure is in no case complicated and, what is more, the work is made possible to be taken out at plural spots, thus it is appliable to even the case that a feed rate of the work is fast.