BOX MAKING DEVICE

PROBLEM TO BE SOLVED: To provide box making device capable of methodically folding a lid part of a box into a fylfot-like shape so as to be a lid.SOLUTION: The box making device comprises a lid part folding mechanism which folds 4 flaps respectively extending from 4 side surfaces of annular side surface parts into a fylfot-like shape and closes an opening of the side surface parts. The lid part folding mechanism comprises a paddle member 21 and a paddle driving part driving the paddle member. The paddle driving part presses the paddle member onto the flap and drives the paddle member so that the flap is folded at an angle of 90° relative to the side surface part. The paddle member comprises: a first contacting part 21a contacting a first tip corner part of the flap; and a second contacting part 21b which is arranged backwards relative to the first contacting part in a folding driving direction upon which the paddle member is driven and contacts a different part to which the tip corner part of the flap does not contact.