Temperature and field dependent Hall resistivity ρ H (T) has been measured for the single crystals of Eu 1 - x Ca x B 6 (x=0.2, 0.4, 0.6, and 0.9). The effective charge carrier density n e f f (T,H) and Hall mobility μ H (T) were derived from the ρ H (T). A large variation in the n e f f (T,H) for x=0.2 and 0.4 compounds was found, while relatively small change for x=0.6 and 0.9 compounds. Analysis of the μ H , based on a small polaronic model, showed that the carrier transport is dominated by the activation of electrons in small polarons. This polaronic scenario of the transport is consistent with the variation of n e f f (T,H).