Box forming apparatus and box forming and packing system

A box forming apparatus that opens a collapsed cardboard sheet, in which a first side surface and a second side surface oppose a third side surface and a fourth side surface, to form a square tubular cardboard box in which the first side surface, the second side surface, the third side surface, and the fourth side surface are consecutive in this order, the box forming apparatus comprising:

• a first holder configured to hold the first side surface of the cardboard sheet;
• a second holder configured to hold the second side surface of the cardboard sheet;
• an arm having a support configured to support the first holder and the second holder, the arm configured to rotate about a rotational center;
• a first mover configured to change a position of the first holder relative to the second holder while the arm is being rotated to open the cardboard sheet;
• and
• a second mover configured to move, in association with rotation of the arm to open the cardboard sheet, the support or the arm in a second direction opposite to a first direction, such that the support is moved in the second direction, when opening of the cardboard sheet is completed, by a predetermined distance relative to a position where the support would be disposed if the support or the arm were not moved by the second mover, the first direction being a direction heading from the rotational center of the arm to a distal end of the arm when the opening of the cardboard sheet is completed.