To provide a milk carton cutting and opening implement with which the work to cut and open a milk carton may be easily and safely carried out.

A cutter blade 4 is obliquely mounted apart a spacing of several millimeters horizontal or nearly horizontally with a backing plate A2. A holding plate 1 is so provided as to be made perpendicular to this backing plate A2. A backing plate B3 is disposed at a point of about half the spacing between the backing plate A2 and the cutter blade 4.