This study is about the design of safety devices to prevent the Quick coupler from detaching or falling, as one of the excavator attachments equipment widely used at construction sites and other industrial sites. The excavator is used by attaching equipment such as buckets, kryasha, shears depending on the characteristics of each work and the Quick coupler is used to quickly replace the attached equipment. At this time, the Quick coupler greatly reduces the detachable and mounted time of attachment equipment, but it can also be the main cause for detachable and falling accidents. Due to each manufacturer has different pin-to-pin distances, when attaching equipment to a Quick coupler, extra space is needed to tighten the moving hook, but there is a limitation because the location of the safety pin is fixed. In addition, the safety connection pin is inserted only when the operator aligns the hole position of the moving hook and the hole position of the Quick coupler body after replacing the equipment, most workers often omit it because it takes time and is annoying. To solve these problems, the Quick coupler's moving hook must be able to bind the connecting pin, and after equipment replacement, the safety device shall be operated automatically so that the connection pin is engaged. In addition, if the Quick coupler's moving hook will bind the connecting pin of the attachment equipment, the safety device should operate regardless of the operator's intention, and the safety device should not be released due to the operator's mistake or error in judgment. This study was conducted to find solutions to prevent detachment and fall accidents of excavator attachment equipment, and it is expected that this study will greatly reduce safety accidents at industrial sites such as excavation, road cleaning, deforestation, and up and down. Because it is difficult to block safety accidents just by approaching that accidents occur due to a lack of safety awareness of workers, design solutions for fundamental problem solving have been derived. Through this study, it is expected that not only will accidents caused by mistakes by workers be reduced, but also productivity will be improved by increasing the convenience of work. In a follow-up study, a prototype will be produced with a dual safety device design for excavator attachment equipment and empirical analysis research based on practical data will be conducted.