We report on numerical calculations of Morse index for figure-eight choreographic solutions to a system of three identical bodies in a plane interacting through homogeneous potential, −1/r a , or through Lennard-Jones-type (LJ) potential, 1/r 12 − 1/r 6 , where r is a distance between the bodies. The Morse index is a number of independent variational functions giving negative second variation S (2) of action functional S. We calculated three kinds of Morse indices, N , N c and N e , in the domain of the periodic, the choreographic and the figure-eight choreographic function, respectively. For homogeneous system, we obtain N = 4 for 0 ≤ a < a 0 , N = 2 for a 0 < a < a 1 , N = 0 for a 1 < a, and N c = N e = 0 for 0 ≤ a, where a 0 = 0.9966 and a 1 = 1.3424. For a = 1, we show a strong relationship between the figureeight choreography and the periodic solution found by Simó through the S (2) . For LJ system, we calculated the index for the solution tending to the figure-eight solution of a = 6 homogeneous system for the period T → ∞. We obtain N , N c and N e as monotonically increasing functions of the gradual change in T from T → ∞, which start with N = N c = N e = 0, jump at the smallest T by 1, and reach N = 12, N c = 4, and N e = 1 for T → ∞ in the other branch.Submitted to: J. Phys. A: Math. Gen.