We give a quantum field theory interpretation of Kontsevich's deformation q
uantization formula for Poisson manifolds. We show that it is given by the
perturbative expansion of the path integral of a simple topological bosonic
open string theory. Its Batalin-Vilkovisky quantization yields a superconf
ormal field theory. The associativity of the star product, and more general
ly the formality conjecture can then be understood by field theory methods.
As an application, we compute the center of the deformed algebra in terms
of the center of the Poisson algebra.