  We investigate effects of the vector interaction appearing in chiral
effective Lagrangians on the chiral and color superconducting (CSC) phase
transitions using Nambu-Jona-Lasinio model. It is shown that the repulsive
density-density interaction coming from the vector term enhances competition
between the chiral symmerty breaking and CSC phase transition: When the vector
coupling is increased, the first order transition between the chiral symmerty
breaking and CSC phase becomes weaker, and the coexisting phase in which both
the chiral and color-gauge symmetries are dynamically broken comes to exisit in
a wider region in the T-\mu plane. We find that the critical line of the first
order transition can have two endpoints for an intermediate range of the vector
coupling.
