Flat bar specimens of Epoxy Resin with a double notch on one edge were subjected to pure bending. The double notch consisted of a primary circular or 60°-V notch and a secondary U notch formed at the base of the primary notch. The effects of the root radius and the depth of the primary notch and also that of the depth of the secondary notch on the stress concentration factors were investigated. The stress concentration factor showed a nearly similar change to that of a single notch when the depth of the secondary notch was varied. This was also true in the case of the variation in the depth of the primary notch. As to the effect of the root radius of the primary notch, the stress concentration factor made a reverse change to that of a single notch. In all cases cxamined, the stress concentration factors of a double notch showed smaller values than the product of the respective stress concentration factor of a primary and a secondary notch.