PURPOSE: To provide a gripper releasing device for placing a paper at a proper time and at a proper place by precisely and reliably opening a gripper at a proper point.

CONSTITUTION: In the selective release of grippers 2 on a conveyor 1, each of them has a movable arm 4 and a stantionary arm 3. The arm 3 and 4 come close to each other to grip a planar product (e.g. a newspaper) therebetween, and separate from each other to release the product. The gripper 2 is biassed toward a closed position and can be moved to the open position by the application of a release force. A rocker cam 8 is provided which can move into a position whereby it urges the movable arm 4 into the open position and into contact with a retaining cam 18. The cam 18 holds the movable arm 4 in the open position for a period of time sufficient to allow the product to be completely released from the gripper 2.