A lid assembly for a container includes a lid engaging device, a transmission assembly mounted on the lid engaging device, and a lid including a first pivotal section and a second pivotal section disposed opposed to each other. The first and second pivotal sections define an imaginary axis “A” extended therebetween, and the first and second pivotal sections are mounted on the lid engaging device. The first pivotal section is engaged with the transmission assembly. The lid is pivoted automatically by the transmission assembly. The lid is pivotal about the imaginary axis “A” and is moveable between an open position that enables items to be put in the container and a closed position in which the lid prevents items to be put in the container.