This paper describes stochastic analysis on a homogenized elastic property of a unidirectional fiber reinforced composite material considering uncertainty in material and geometrical properties of component materials. The influence of the microscopic uncertainties on the stochastic characteristics of a homogenized elastic property is analyzed with the perturbation-based analysis using the equivalent inclusion method. Especially, influence of a volume fraction variation on the stochastic characteristics is discussed in this paper. Also, as an example of a design considering the influence of a volume fraction variation, a limit of the random variation of the volume fraction of fiber for controlling a random variation of a homogenized elastic property of a composite to be less than random variations of elastic properties of component materials is discussed.