simply by lightly pushing the press member 4 toward the body 1 fig1 shows a seventh embodiment of this invention herein the recess 4b of the sixth embodiment is replaced by an annular recess 4c which can engage with the cutter 3 the remaining features being the same as those of the first embodiment in this case also the film 2 can easily be cut simply by lightly pushing the press member 4 toward the blade 30 fig1 shows an eighth embodiment of this invention in this case the press member 4 of the first embodiment is replaced by a cylindrical press member 40 which fits on the outer circumference of the cutter 3 the remaining features being the same as those of the first embodiment when the press member 40 is pressed on the cutter 3 the lower end of the annular press member 40 gives a tensile stress to the film 2 on the outer circumference of the blade 30 when the press member 40 is moved further in the direction of the body 1 the inner circumference of the press member 40 fits on the outer circumference of the blade 30 and the blade 30 cuts the film 2 according to this embodiment the press member 40 does not come in contact with the blade 30 so the durability of the blade 30 and press member 40 are improved fig1 shows a ninth embodiment of this invention herein.