  Stochastic Variational Method (SVM) is the generalization of the variation
method to the case with stochastic variables. In the series of papers, we
investigate the applicability of SVM as an alternative field quantization
scheme. Here, we discuss the complex Klein-Gordon equation. In this scheme, the
Euler-Lagrangian equation for the stochastic fields leads to the functional
Schroedinger equation, which in turn can be interpreted as the ideal fluid
equation in the functional space. We show that the Fock state vector is given
by the stationary solution of these differential equations and various results
in the usual canonical quantization can be reproduced, including the effect of
anti-particles. The present formulation is a quantization scheme based on
commutable variables, so that there appears no ambiguity associated with the
ordering of operators, for example, in the definition of Noether charges.
