The ionic conductivity (σ_ac) and the real part of complex dielectric permittivity (ε′) of F conductor NH₄Sn₂F₅ have been investigated between 300 and 380 K in the frequency range from 20 to 3.2 · 10¹⁰ Hz. The crystals NH₄Sn₂F₅ at the temperatures T₁ = 343 K and T₂ = 357 K undergo two superionic phase transitions, accompanied by the anomalies of σ_ac and ε′. At room temperature and electric field frequency ν = 10³ Hz, σ_ac = 5 · 10^-2 S/m and its activation energy ΔE₁ = 0.47 eV; at temperature T ≥ 357, K σ_ac(T) changes with activation energy ΔE₂ = 0.34 eV. In the temperature range 343 ≤ T ≤ 357 K, σ_ac(T) dependence does not obey Arrhenius law. In this frequency region two relaxation dispersions of σ_ac and ε′ attributed to the ion transport in the grain and grain boundaries of our polycrystals have been found.