Deformation of stretched zones during stable crack growth (stages II and III) in JIC tests was examined by observing stereographically relations between apparent critical stretched zone width (SZWC) and crack tip opening desplacement. The average value of the apparent SZWC along the crack from continued to increase with increase in J during the extension of tear region along the crack from from 20%, at which crack initiation and SZWC were defined by the JSME standard, to 100% in length (stage II). In the stable tear crack growth stage (stage III), SZWC was also deformed consiferable with low-strength high-toughness steels and, to a lesser extent, with high strength high-SZWC steel and medium-strength steel, but not with high-strength low-SZWC steel. A new procedure of SZY method was proposed to obtain JIC values compative with those by the R-curve method, by avoiding errors due to the SZWC deformation.