Maximal mass of relativistic star is one of the quantities
which may distinguish modified gravity theories
because it is strongly influenced by the short-range behavior of gravitation.
We derive modified Tolman-Oppenheimer-Volkoff equations for the de Rham-Gabadadze-Tolley (dRGT) massive gravity with the flat reference metric. We find that new constraint equations appear and that the maximum masses in the minimal model of dRGT massive gravity become smaller than those in the general relativity.