The ATLAS experiment at the Large Hadron Collider is investigating why the Universe is dominated by an unknown type of matter called dark matter. There is a lot of cosmological evidence of the existence of dark matter, but very little is known about its nature. The favourite candidate for dark matter are weakly interacting particles which can be produced in high energy proton-proton collisions at the Large Hadron Collider. This lecture will review the search for these invisible, and yet very important, particles with the ATLAS experiment at the CERN Large Hadron Collider. The theoretical model of SuperSymmetry is used to model the behaviour of the dark matter particles, and you will be shown how ATLAS once again could uncover exciting physics phenomena in next few years.