To improve the efficiency by integrating an opening motion of a bag by a vacuum cup with a wide-opening motion of the same bag by a separating motion of opening/closing arms.

Rotary links 14 in which a vacuum cup 15 is fixed to each lower end are supported in an oscillating manner with a pivotably-attached pin by a pair of opening/closing arms 11 supported by a support pin 10. The axis 21 of the rotary 21 is inclined, and when both opening/closing arms 11 are separated from each other by the power of the support pin 10, the rotary link 14 is rotated in a returning manner in the direction to keep the self-weight balance, and inclines a vacuum cup 15, and a mouth edge of a bag 17 is split into two. The bag is widely opened by the further separation of the opening/ closing arms 11.