a vaccum type separator plate is therefore not necessarily used concerning the touching member 32 the vacuum type one has been also adopted such a vacuum type touching member is not always adopted if a touching member is made up of rubber hard to slip or material whose surface is adhesive as well as the separator plate described above as illustrated in the drawings the claw 37 which hooks the upper sheet of a bag opening has been adopted in addition to the vacuum type touching member in case a vacuum type touching member is used however it is possible to lift the upper sheet of a bag opening by means of only the touching member so that the bag is opened without using such a claw the illustrated touching member 32 has been shown as one of sliding the upper sheet of a bag opening by its swinging motion however a touching member may be composed as one which slides the upper sheet merely by its horizontal displacement for the pusher device 10 furthermore there may be adopted these different in shape and structure in the apparatus according to the present invention as has been described above one corner of the opening of an uppermost bag of stacked bag is picked up and a separator plate is inserted from the same corner between the uppermost bag and a next bag stacked thereunder and then a touching member is brought from above into contact with the opening of the bag carried on the separator plate to slide the upper film of the bag opening toward the bottom of the bag and the thus slidden upper egde is lifted to open the bag and then an.