For a three-dimensional eight-vertex model with energy parameters satisfying the condition ε1+ε2=ε3+ε4, all the critical exponents have been calculated:α=α′=0,β=1/4,δ=7,γ=1/2,γ′=3/2,ν=ν′=1,η=3/2. These do not satisfy the scaling law, the reason is that the correlative region of polarization contracts from the crystal planes (1, 1, 1) and (1, 1, 1) to the crystal axis 1, 0, 1 at the critical point.