The precision on the measurement of the mass of the top quark has reached the level of about 500 MeV (0.3%). This is not an easy accomplishment, neither on the experimental front, for a particle whose final state includes jets and neutrinos, nor from the theory point of view given that it is a strongly interacting particle. Yet high precision is important because the top quark enters much of the dynamics of other particles in the standard model, and has an important relationship with the Higgs boson. The seminar will discuss the challenges of the top quark mass determination, and the recent advancements of the ATLAS experiment, including direct measurement from the top decay and indirect determination from cross sections.