This paper describes an evaluation method for nonwoven fabrics using an image analysis technique. Fifty nonwoven fabrics such as coverstocks, filters, and interlinings were used for this study. They were made from polyester, polyethylene, polypropylene, and rayon fibers using chemical, meltblown, spunbond, and thermal bonding systems. Two properties (air permeability and tensile property) of the nonwoven fabrics were evaluated in this study. Each circle radius inscribed in the polygons of the pores in the nonwoven fabrics was assumed to have gamma function. The mean and variance of the radius were related to air permeability. Fiber orientation was obtained from the information of the image and then, the tensile moduli of nonwoven fabrics were predicted by fiber orientation density function and were compared with experimental values.