  In this paper, we observe the amalgamated free product structure of a Graph
W*-probability space. In [16] and [17], we already observed the operator-valued
freeness conditions on a graph W*-algebra. By using the conditions, we will
consider the amalgamated free product structure of a graph W*-algebra. In
particular, we can make the algebra be blocked, by so-called the loop free
blocks (D_G-semicircular blocks) and non-loop blocks (R-diagonal blocks).
Finally, we can see the the graph W*-algebra is the free product of edge blocks
of the algebra.
