The difference in the electrical conduction behavior of various kinds of M(n)Zr2n(PO4)3n (M(n) = alkali metals, alkaline earth metals, Ag, Mn, Co, Ni, Zn, Cd, Pb, Al, Ga, and In) compounds (abbreviated as MZP) has been investigated by using frequency dispersion analysis. The conductivity of MZP with a NASICON-type structure mainly depended on the hopping rate of mobile cation; the conductivity of MZP with a beta-Fe2(SO2)3-type structure was more affected by the mobile ion concentration than that with the NASICON-type one. These conclusions agree well with those obtained from crystallographic investigation.