We investigate bifurcation and chaos observed in coupled BVP neurons with external impulsive forces. Although the single neuron without the external force has only one equilibrium point, combining these n (n 2 3) neurons unidirectionally in a ring, n-phase periodic solutions are generated. Applying the impulsive forces, successive period-doubling bifurcations of the n-phase solution occur and chaotic states, namely n-phase chaos, appear. When n = 2 and 3, we find the parameter regions in which the switching phenomena of burst firing are observed. Moreover, the mechanisms of the switching phenomena are clarified by numerical bifurcation analysis.