  We study on the property of 3-point correlation functions of 2-dim A_{N-1}
Toda field theory, and show the correspondence with the 1-loop part of
partition function of 4-dim N=2 SU(N) quiver gauge theory. As a result, we can
check successfully the 1-loop part of AGT-W relation for all the cases of SU(N)
quiver gauge group.
