The orbital dynamics of the homogeneous superfluid 3He-A is investigated through microscopic calculation of the response function for the l-vector of the Cooper pairs. It is shown that Leggett and Takagi's phenomenological theory is justified in the region Δ(T)τ≫1 and ωτ≪1. However a critical exponent of the relaxation time of the l-vector in the region Δ(T)τ≪1 is zero in contrast with their theory. The intrinsic angular momentum has the same form in the two frequency regions.