A backpack work apparatus comprises a back carrier frame; a drive motor mounted on the back carrier frame; a work tool driven by the drive motor; a right and left shoulder straps; a chest strap linking the intermediate points of the right and left shoulder straps; and an emergency release buckle device provided at the point where the chest strap is coupled to the intermediate point of the left shoulder strap, which is divided by the buckle device into two parts, an upper strap and a lower strap. The buckle device normally buckles the chest strap, the upper strap and the lower strap, and is capable of releasing the lower strap and the chest strap from the upper strap via a one part motion in an emergency.