To provide an enclosing apparatus of a space saving type which does not separately perform the folding of a paper and the enclosing of it into an envelope at different positions, and can enclose the paper into the envelope under a state wherein the paper is neatly folded to a suitable size even when the paper is a thin paper.

This enclosing apparatus 1 includes: a paper inserting means 6 which holds a paper P into a peripheral shape with the axis as the center, and inserts the paper P into the envelope E by moving the paper P in parallel with the axis; an opening expanding means 20 which expands the opening of the envelope; and an envelope pressing roller 23 which folds the paper by adjusting the paper to the size of the envelope by crushing the paper in the envelope in such a manner that the envelope in which the paper has been inserted is carried by pinching the envelope.