Crystallographic features of La 1 - x Sr x MO 3 with M=Cr and Fe in the vicinity of the R3c/Pbnm phase boundary have been examined mainly at room temperature by transmission electron microscopy. When the Sr content x increases from x=0, the change in crystal structure from Pbnm to R3c was confirmed to occur at room temperature in La 1 - x Sr x CrO 3 around x=0.2. In La 1 - x Sr x FeO 3 , on the other hand, the incommensurate phase was found to exist between the Pbnm and the R3c phases. The analysis of the electron diffraction patterns obtained in the work indicated that the normal structure of the incommensurate structure and the direction of the modulation could, respectively, be identified as the Pbnm structure and one of the <323> directions. It was also suggested that the rotational displacement of the oxygen octahedra involved in the Pbnm structure should be modulated in the incommensurate structure.