  A general framework for applying the pp-wave approximation to holographic
calculations in the AdS/CFT correspondence is proposed. By assuming the
existence and some properties of string field theory (SFT) on $AdS_5 \times
S^5$ background, we extend the holographic ansatz proposed by Gubser, Klebanov,
Polyakov and Witten to SFT level. We extract relevant information of assumed
SFT on $AdS_5 \times S^5$ from its approximation, pp-wave SFT. As an explicit
example, we perform string theoretic calculations of the conformal three point
functions of the BMN operators. The results agree with the previous
calculations in gauge theory. We identify a broad class of field redefinitions,
including known ambiguities of the interaction Hamiltonian, which does not
affect the results.
