We investigated the central mass distribution of the luminous infrared galaxy NGC 3256 at a distance of 35 Mpc by using
CO(1-0) observations of the Atacama Large Millimeter and sub-millimeter Array (ALMA) and near-IR data of the Two
Micron Sky Survey (2MASS). We found that there is a huge amount of invisible dynamical mass (4.48 × 1010 ) in the
central region of the galaxy. The invisible mass is likely caused by some dark matter, which might have a cuspy dark
matter profile. We note that this dark matter is difficult to explain with the conventional Modified Newtonian Dynamics
(MOND) model, which is only applicable at a low acceleration regime, whereas the acceleration at the central region
of the galaxy is relatively strong. Therefore, this discovery might pose a challenge to the conventional MOND models.