The invention generally relates to a closure device for waste containers, particularly residential or commercial waste containers. In particular, the invention relates to a waste container closure device which prevents the lid from opening when the container is accidentally tipped over on its side. The closure device contains two straps: a right side strap and a left side strap; two mounting devices: a right side mounting device and a left side mounting device; and one or more elastic members. Those components cooperate to allow the straps to connect over the top of the lid of the waste container to remain closed when it is accidentally tipped on its side.