Abstract: A gun sling restraint device for a backpack shoulder strap is an apparatus that allows a user to hang the gun sling of a rifle on their backpack shoulder strap and comprises a platform, a sling hook, and an attachment strap. The platform is a rigid panel that braces the apparatus against the top surface of the backpack shoulder strap. The platform properly positions the sling hook on the user's shoulder so that the user can hang the gun sling on the apparatus. The sling brace is connected normal to the platform but then angles toward the user's neck in order to prevent the gun sling from falling off the apparatus. The attachment strap connects to the platform by weaving through a pair of holes that are located on the platform and wraps around the backpack shoulder strap as a means to situate the platform on the backpack shoulder strap.