Electrical conduction in 1 mol% Sr-doped Bi-4(SiO4)(3) with the eulytite-type structure at elevated temperatures was investigated with conductivity measurements. Conductivity of the material under wet condition was higher than that under dry condition, and were 1.2 x 10(-6) - 9.7 x 10(-5) S cm(-1) at 500-850 degrees C. From H/D isotope effects and p(O-2)-dependencies of the conductivity, it was found that the Sr-doped Bi-4(SiO4)(3) exhibited protonic conduction at all the temperatures investigated while contribution of p-type conduction became significant with increasing p(O-2) and/or temperature. Protonic and p-type conductions in the material were discussed in terms of defect equilibria.