PURPOSE: To downsize an apparatus to reduce an installation occupied area, simplify a structure of a blade for cutting a bag-like flexible container bag filled with cement or the like, simplify maintenance to shorten time required therefor, and reduce product cost to a low price.

CONSTITUTION: An inclined knife 31 positioned below an opener casing 1 is provided between a stretchable canvas shutter 3 and a powder carrying feeder 18, wherein the inclined knife 31 has an upward blade higher at a center part and becoming lower toward outer ends. On the other hand, a piercing needle 32 is provided which is positioned higher than the inclined knife 31, whose tip is directing upward and which makes a hole on a bottom of the flexible container bag.