  After introducing Berezin integral for polynomials of odd variables, we
develop the elementary integral calculus based on supersmooth functions on the
superspace ${\mathfrak{R}}^{m|n}$. Here, ${\mathfrak{R}}$ is the
Fr\'echet-Grassmann algebra with countably infinite Grassmann generators, which
plays the role of real number field ${\mathbb{R}}$. As is well-known that the
formula of change of variables under integral sign is indispensable not only to
treat PDE applying funtional analytic method but also to introduce analysis on
supermanifolds. But, if we define naively the integral for supersmooth
functions, there exists discrepancy which should be ameliorated. Here, we
extend the contour integral modifying the parameter space introduced basically
by de Witt, Rogers and Vladimirov and Volovich
