PURPOSE: To provide a cutter which cut-opens the edges of a variety of paper, strings, etc., speedily and safely.

CONSTITUTION: A cutter is equipped with a pair of holding bodies 5 and 6 arranged in layered state each other, a pair of opened/closed bodies 10 and 11 which are installed in a turnable manner at the edge parts of both the holding bodies 5 and 6 and form a cut opened region through which the cut opened part of a cut opened article such as paper in superposed state or in box shape, etc., passes, and a cutter blade 12 installed at the edge parts of the holding bodies 5 and 6, in the state where the cutting edge for cut-opening the cut opened article is set close to the cut opened region. With this constitution, the cut opening for the edges of a variety of paper and the cutting work for strings, etc., can be executed speedily and safely, and the efficiency can be improved.