It is very important for structural designer to evaluate properly the brittle fracture characteristics of steel plates. Though comparatively reliable data can be obtained from so called large scale laboratory tests, they are unsuitable for commercial acceptance test methods from the view point of efficiency, economy, etc. On the other hand the interpretation of current commercial test such as Charpy test is rather obscure and evaluation of notch toughness of materials in relation to service failure depends almost solely on accumulation of experiences in service performances with the lack of accepted theoretical basis. The present authors previously reported of the sucessful results of fracture mechanics analysis on the double tension test (brittle fracture propagation test) and new interpretation and method of analysis for such test results and further insisted that similar method of analysis and correlation study should be made on small size test. In this report the results of analysis based on abovementioned considerations are discussed in comparison with the results from double tension test. Though there are something to be improved for the practical purposes, fundamental characteristics of the small size test of this sort have been clarified to some extent from fracture mechanics view point and some important data were obtained which will be available for future improvements in small size tests.