A paper packing box is provided to configure a structurally solid box shape just by folding one paper board along the folding lines thereof, and to store contents, like agricultural products, damaged easily by an outside shock, safely so as to heighten a convenience of distribution and transportation. A paper packing box comprises: a first board(10), having a first lateral wall(11) with a hole for a catch, and a first bottom(15) which is extended from a lower end of the first lateral wall and folded at a right angle along a horizontal folding line(hf), as well as formed in a trapezium shape; a second board(20), having a second lateral wall(21) which is extended from one end of the first lateral wall, and a second bottom(25) which is extended from the second lateral wall and folded at a right angle along the horizontal folding line; a third board(30), having a third lateral wall(31) and a third bottom(35) both of which have a shape corresponding to those of the first board; a fourth board(40) having a fourth l
