This paper is concerned with the effect of filler to a crack which, has occurred in the polymer composite materials under loading. Model specimens for photoelastic test were made with epoxy resin plate in which a small copper plate was inserted as a filler into central transverse axis, and varied the length of copper plate from 0 to 80mm. Measurement of stress concentration factor of simple epoxy plate was carried out under tension, bending and bi-axial loading respectively, according to the variation of depth, angle and root radius of notch. And it was then compared to stress concentration factor of a specimen notched in the same way in which a copper plate was inserted. The results showed that under tension the values of stress concentration factor of copper plate inserted specimen were lower than un-inserted epoxy plate, but under bending the values were represented reversely owing to the position of copper plate in specimen. In bi-axial loading the values were observed to be between the values under tension and under bending.