Let a be a real number satisfying 0 < a < π. We denote by M n (a) the configuration space of regular spherical n-gons with side-lengths a. The purpose of this paper is to determine χ(M n (a)) for all a and odd n. To do so, we construct a manifold X n and a function µ : X n → R such that µ −1 (a) = M n (a). In fact, the function µ is different from the well-known "wall-crossing" function. We determine the index of each critical point of µ. Since a level set is obtained by successive Morse surgeries, we can determine χ(M n (a)).2000 Mathematics Subject Classification. Primary 58E05; Secondary 58D29.