PROBLEM TO BE SOLVED: To provide a wraparound type packing box which can be easily folded.SOLUTION: A packing box 1 comprises a bottom plate 10, a pair of front and rear end walls 11, 12, a top plate 15, and a pair of left and right side walls 13, 14, and an opening 17 is formed on the top plate 15. The side walls 13, 14 include front and rear side part flaps 21, 22, an upper side flap 31, and a lower side flap 32. The upper side flap 31 and the lower side flap 32 are joined to exterior surfaces of the side part flaps 21, 22. First horizontal rules L9, L10 are formed on midship parts of the bottom plate 10 and the top plate 15 in a cross direction, and second horizontal rules L11, L12 are formed on midship parts of the upper side flap 31 and the lower side flap 32 in a cross direction. An upper cutting line 41, which extends from the opening 17 to front and right, and left and right corners, is formed on the top plate 15. Lower cutting lines 42, 42, which extend from an intermediate part of an upper edge part
